**Understanding the Gauge plots**

The gauge plots that accompany the indicator time series are meant to reflect the current status of that ecosystem component at the regional or national level. The numerical scores are determined as the percentile rank of the average (mean) value of that indicator over the last five years of the time series, relative to the series as a whole. The values typically represent quantitative scores, with more desirable conditions in the darker blue. Thus, some gauges are "right-handed" with the higher values being in darker blue, whereas other gauges are "left-handed" with lower values being in darker blue (indicating that lower values are preferable). In some instances (e.g. climate measures), the scores represented are unitless and are presented as two-way gauges, indicating that either high or low scores are observed, implying neither higher nor lower values are necessarily preferred.

**Understanding the Time series plots**

Time series plots show the changes in each indicator as a function of time, over the period 1980-present. Each plot also shows horizontal lines that indicate the median (middle) value of that indicator, as well as the 10th and 90th percentiles, each calculated for the entire period of measurement. Time series plots were only developed for datasets with at least 10 years of data. Two symbols located to the right of each plot describe how recent values of an indicator compare against the overall series. A black circle indicates whether the indicator values over the last five years are on average above the series 90th percentile (plus sign), below the 10th percentile (minus sign), or between those two values (solid circle). Beneath that an arrow reflects the trend of the indicator over the last five years; an increase or decrease greater than one standard deviation is reflected in upward or downward arrows respectively, while a change of less than one standard deviation is recorded by a left-right arrow.

#### Alaska - Eastern Bering Sea

Between 2016 and 2021 the average integrated degree-day value was much higher than the median integrated degree-day value between 1982 and 2021.

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for Alaska’s Eastern Bering Sea region. During the last five years there has been no trend, though values have remained above the 90th percentile of all observed data in the time series.

**Description of Gauge: **The gauge value of 90 indicates that between 2016 and 2021 the average integrated degree-day value was much higher than the median integrated degree-day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

The marine heatwave data shown here are calculated by NOAA’s National Centers for Environmental Information using Optimum Interpolation Sea Surface Temperature (OISST) data. The NOAA 1/4° OISST is a long term Climate Data Record that incorporates observations from different platforms (satellites, ships, buoys and Argo floats) into a regular global grid. The dataset is interpolated to fill gaps on the grid and create a spatially complete map of sea surface temperature. Satellite and ship observations are referenced to buoys to compensate for platform differences and sensor biases.

**Data Background and Caveats:**

Heatwave metrics are calculated using OISST, a product that uses some forms of interpolation to fill data gaps. Heatwaves are defined by Hobday et al., 2016 as distinct events where SST anomaly reaches the 90th percentile in a pixel for at least 5 days, separated out by 3 or more days.

#### Alaska - Gulf of Alaska

Between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for Alaska’s Gulf of Alaska region. During the last five years there has been no trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 85 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

The marine heatwave data shown here are calculated by NOAA’s National Centers for Environmental Information using Optimum Interpolation Sea Surface Temperature (OISST) data. The NOAA 1/4° OISST is a long term Climate Data Record that incorporates observations from different platforms (satellites, ships, buoys and Argo floats) into a regular global grid. The dataset is interpolated to fill gaps on the grid and create a spatially complete map of sea surface temperature. Satellite and ship observations are referenced to buoys to compensate for platform differences and sensor biases.

**Data Background and Caveats:**

Heatwave metrics are calculated using OISST, a product that uses some forms of interpolation to fill data gaps. Heatwaves are defined by Hobday et al., 2016 as distinct events where SST anomaly reaches the 90th percentile in a pixel for at least 5 days, separated out by 3 or more days.

#### Alaska - Chukchi Sea

Between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for Alaska’s Chukchi Sea region. During the last five years there has been a significant downward trend and values have remained above the 90th percentile of all observed data in the time series.

**Description of Gauge: **The gauge value of 90 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

The marine heatwave data shown here are calculated by NOAA’s National Centers for Environmental Information using Optimum Interpolation Sea Surface Temperature (OISST) data. The NOAA 1/4° OISST is a long term Climate Data Record that incorporates observations from different platforms (satellites, ships, buoys and Argo floats) into a regular global grid. The dataset is interpolated to fill gaps on the grid and create a spatially complete map of sea surface temperature. Satellite and ship observations are referenced to buoys to compensate for platform differences and sensor biases.

**Data Background and Caveats:**

Heatwave metrics are calculated using OISST, a product that uses some forms of interpolation to fill data gaps. Heatwaves are defined by Hobday et al., 2016 as distinct events where SST anomaly reaches the 90th percentile in a pixel for at least 5 days, separated out by 3 or more days.

#### Gulf of Mexico

Between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for the Gulf of Mexico region. During the last five years there has been a significant downward trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 85 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Northeast

Between 2016 and 2021 the average integrated degree-day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for the Northeast region. During the last five years there has been no trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 88 indicates that between 2016 and 2021 the average integrated degree-day value was very high compared to the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Southeast

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for the Southeast region. During the last five years there has been no trend and values have remained above the 90th percentile of all observed data in the time series.

**Description of Gauge: **The gauge value of 90 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### California Current

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for the California Current region. During the last five years there has been no trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 78 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### American Samoa

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for American Samoa. During the last five years there has been no trend and values have remained above the 90th percentile of all observed data in the time series.

**Description of Gauge: **The gauge value of 90 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Caribbean

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for the Caribbean region. During the last five years there has been no trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 82 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Guam & the Northern Mariana Islands

Between 2016 and 2021 the average integrated degree day value was significantly higher than the median average integrated degree day value between 1982 and 2021.

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for the Guam and CNMI region. During the last five years there has been a significant increasing trend and values have remained above the 90th percentile of all observed data in the time series.

**Description of Gauge: **The gauge value of 92 indicates that between 2016 and 2021 the average integrated degree day value was significantly higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Hawaiian Insular LME

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for the Hawaiian Insular LME region. During the last five years there has been no trend and values have remained above the 90th percentile of all observed data in the time series.

**Description of Gauge: **The gauge value of 90 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Howland & Baker Islands

Between 2016 and 2021 the average integrated degree day value was higher than the median average integrated degree day value between 1982 and 2021.

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for Howland and Baker Islands. During the last five years there has been no trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 73 indicates that between 2016 and 2021 the average integrated degree day value was higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Jarvis Island

Between 2016 and 2021 the average integrated degree day value was significantly higher than the median average integrated degree day value between 1982 and 2021.

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for Jarvis Island. During the last five years there has been a significant decreasing trend and values have remained above the 90th percentile of all observed data in the time series.

**Description of Gauge: **The gauge value of 93 indicates that between 2016 and 2021 the average integrated degree day value was significantly higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Johnson Atoll

Between 2016 and 2021 the average integrated degree day value was significantly higher than the median average integrated degree day value between 1982 and 2021.

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for Johnson Atoll. During the last five years there has been no trend and values have remained above the 90th percentile of all observed data in the time series.

**Description of Gauge: **The gauge value of 95 indicates that between 2016 and 2021 the average integrated degree day value was significantly higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Kingman Reef & Palmyra Atoll

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for Kingman Reef and Palmyra Atoll region. During the last five years there has been no trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 89 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Wake Island

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for the Wake Island region. During the last five years there has been no trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 87 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Great Lakes

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for the Great Lakes region. During the last five years there has been a significant upward trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 85 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Lake Ontario

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for Lake Ontario. During the last five years there has been a significant upward trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 82 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Lake Erie

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for Lake Erie. During the last five years there has been no significant trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 82 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Lake Huron

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for Lake Huron. During the last five years there has been a significant upward trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 88 indicates that between 2016 and 2021 the average integrated degree day value was significantly higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Lake Michigan

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for Lake Michigan. During the last five years there has been a significant upward trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 85 indicates that between 2016 and 2021 the average integrated degree day value was significantly higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Lake Superior

*Values indicate c**umulative annual heatwave intensity and duration in a region in degree-days*

**Description of Time Series: **This time series shows the average integrated degree day value for Lake Superior. During the last five years there has been a significant upward trend and values have remained between the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 85 indicates that between 2016 and 2021 the average integrated degree day value was much higher than the median average integrated degree day value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year integrated degree day value is very low compared to the median value.
- 10 - 25: The five-year integrated degree day value is much lower than the median value.
- 25 - 50: The five-year integrated degree day value is lower than the median value.
- 50: The five-year integrated degree day value average equals the median value.
- 50 - 75: The five-year integrated degree day value is higher than the median value.
- 75 - 90: The five-year integrated degree day value is much higher than the median value.
- 90 - 100: The five-year integrated degree day value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Alaska - Eastern Bering Sea

The gauge value of 90 indicates that between 2016 and 2021 the average area fraction value was very high compared to the median area fraction between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for Alaska’s Eastern Bering Sea Region. During the last five years heatwave coverage has trended downward, and the five-year average is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 90 indicates that between 2016 and 2021 the average area fraction value was very high compared to the median area fraction between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

Heatwave metrics are calculated using OISST, a product that uses some forms of interpolation to fill data gaps. Heatwaves are defined by Hobday et al., 2016 as distinct events where SST anomaly reaches the 90th percentile in a pixel for at least 5 days, separated out by 3 or more days

#### Alaska - Gulf of Alaska

The gauge value of 85 indicates that between 2016 and 2021 the average area fraction value was much higher than the median area fraction between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series:** This time series shows the monthly heatwave spatial coverage for Alaska’s Gulf of Alaska Region. During the last five years there has been no significant trend and the five-year average is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 85 indicates that between 2016 and 2021 the average area fraction value was much higher than the median area fraction between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

Heatwave metrics are calculated using OISST, a product that uses some forms of interpolation to fill data gaps. Heatwaves are defined by Hobday et al., 2016 as distinct events where SST anomaly reaches the 90th percentile in a pixel for at least 5 days, separated out by 3 or more days

#### Alaska - Chukchi Sea

The gauge value of 89 indicates that between 2016 and 2021 the average area fraction value was much higher than the median area fraction between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for Alaska’s Chukchi Sea Region. During the last five years there has been a significant downward trend and the five-year average is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 89 indicates that between 2016 and 2021 the average area fraction value was much higher than the median area fraction between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

Heatwave metrics are calculated using OISST, a product that uses some forms of interpolation to fill data gaps. Heatwaves are defined by Hobday et al., 2016 as distinct events where SST anomaly reaches the 90th percentile in a pixel for at least 5 days, separated out by 3 or more days

#### Gulf of Mexico

The gauge value of 90 means that recent heatwave area coverage is very high compared to the median value since the start of this record in 1982.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for the Gulf of Mexico Region. During the last five years there has been no significant trend and the five-year average is higher than the 90th percentile of all observed data in the time series.

**Description of Gauge: ****T**he gauge value of 90 means that recent heatwave area coverage is very high compared to the median value since the start of this record in 1982.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Northeast

The gauge value of 88 indicates that between 2016 and 2021 the average area fraction value was much higher than the median value between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for the Northeast Region. During the last five years marine heatwave coverage has trended upward and the five-year average is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 88 indicates that between 2016 and 2021 the average area fraction value was much higher than the median value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Southeast

The gauge value of 88 indicates that between 2016 and 2021 the average area fraction value was much higher than the median value between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for the Southeast Region. During the last five years there has been no significant trend and the five-year mean is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 88 indicates that between 2016 and 2021 the average area fraction value was much higher than the median value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### California Current

The gauge value of 83 indicates that between 2016 and 2021 the average five-year area fraction value is much higher than the median area fraction between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for the California Current Region. During the last five years there has been no significant trend and the five-year mean is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 83 indicates that between 2016 and 2021 the average five-year area fraction value is much higher than the median area fraction between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Caribbean

The gauge value of 89 indicates that between 2016 and 2021 the average area fraction value was much higher than the median area fraction between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for the Caribbean Region. During the last five years there has been no significant trend and the five-year mean is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 89 indicates that between 2016 and 2021 the average area fraction value was much higher than the median area fraction between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### American Samoa

The gauge value of 89 means that recent heatwave area coverage is much higher than the median value since the start of this record in 1982.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for the American Samoa Region. During the last five years there has been no significant trend and the five-year mean is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 89 means that recent heatwave area coverage is much higher than the median value since the start of this record in 1982.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Guam + CNMI

The gauge value of 94 means that recent heatwave area coverage value was very high compared to the median value between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for Guam and CNMI Region. During the last five years heatwave coverage has trended upward and the five-year mean is higher than the 90th percentile of all observations in this record.

**Description of Gauge: **The gauge value of 94 means that recent heatwave area coverage value was very high compared to the median value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Hawaiian Insular LME

The gauge value of 92 indicates that between 2016 and 2021 the average area fraction value was very high compared to the median area fraction between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for the Hawaiian Insular LME Region. During the last five years heatwave coverage has trended upward and the five-year mean is higher than the 90th percentile of all observations in this record.

**Description of Gauge: **The gauge value of 92 indicates that between 2016 and 2021 the average area fraction value was very high compared to the median area fraction between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Howland & Baker Islands

The gauge value of 84 indicates that between 2016 and 2021 the average area fraction value was much higher than the median value between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for Howland and Baker Islands. During the last five years there has been no significant trend and the five-year mean is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 84 indicates that between 2016 and 2021 the average area fraction value was much higher than the median value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Jarvis Island

The gauge value of 82 indicates that between 2016 and 2021 the average area fraction value was much higher than the median value between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for Jarvis Island. During the last five years there has been no significant trend and the five-year mean is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 82 indicates that between 2016 and 2021 the average area fraction value was much higher than the median value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Johnson Atoll

The gauge value of 92 indicates that between 2016 and 2021 the average area fraction value was very high compared to the median value between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for Johnson Atoll. During the last five years there has been no significant trend but the five-year mean is higher than the 90th percentile of all observations in this record.

**Description of Gauge: **The gauge value of 92 indicates that between 2016 and 2021 the average area fraction value was very high compared to the median value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Kingman Reef & Palmyra Atoll

The gauge value of 89 indicates that between 2016 and 2021 the average area fraction value was much higher than the median area fraction between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for Kingman Reef and Palmyra Atoll. During the last five years there has been a significant downward trend and the five-year average is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 89 indicates that between 2016 and 2021 the average area fraction value was much higher than the median area fraction between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Wake Island

The gauge value of 87 indicates that between 2016 and 2021 the average area fraction value was much higher than the median value between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for Wake Island. During the last five years there has been no significant trend and the five-year average is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 87 indicates that between 2016 and 2021 the average area fraction value was much higher than the median value between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Great Lakes

Under Construction

#### Lake Ontario

The gauge value of 39 indicates that between 2016 and 2021 the average area fraction value was lower than the median area fraction between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for Lake Ontario. During the last five years there has been no significant trend and the five-year average is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 39 indicates that between 2016 and 2021 the average area fraction value was lower than the median area fraction between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Lake Erie

The gauge value of 100 means that recent heatwave area coverage is as high as it has ever been since the start of this record in 1982.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for Lake Erie. During the last five years there has been no significant trend and the five-year average is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 100 means that recent heatwave area coverage is as high as it has ever been since the start of this record in 1982.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Lake Huron

The gauge value of 40 indicates that between 2016 and 2021 the average area fraction value was lower than the median area fraction between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for Lake Huron. During the last five years there has been no significant trend and the five-year average is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 40 indicates that between 2016 and 2021 the average area fraction value was lower than the median area fraction between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Lake Michigan

The gauge value of 48 indicates that between 2016 and 2021 the average area fraction value was lower than the median area fraction between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for Lake Michigan. During the last five years heatwave coverage has trended upward but the five-year average is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 48 indicates that between 2016 and 2021 the average area fraction value was lower than the median area fraction between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

#### Lake Superior

The gauge value of 42 indicates that between 2016 and 2021 the average area fraction value was lower than the median area fraction between 1982 and 2021.

*Values indicate monthly percent of an LME area affected by heatwave*

**Description of Time Series: **This time series shows the monthly heatwave spatial coverage for Lake Superior. During the last five years heatwave coverage has trended upward but the five-year average is within the 10th and 90th percentiles of all observed data in the time series.

**Description of Gauge: **The gauge value of 42 indicates that between 2016 and 2021 the average area fraction value was lower than the median area fraction between 1982 and 2021.

*Gauge Values*

- 0 - 10: The five-year area fraction value is very low compared to the median value.
- 10 - 25: The five-year area fraction value is much lower than the median value.
- 25 - 50: The five-year area fraction value is lower than the median value.
- 50: The five-year area fraction value average equals the median value.
- 50 - 75: The five-year area fraction value is higher than the median value.
- 75 - 90: The five-year area fraction value is much higher than the median value.
- 90 - 100: The five-year area fraction value is very high compared to the median value.

**Indicator Source Information:**

**Data Background and Caveats:**

## Additional Resources

#### NOAA PSL Marine Heatwaves

Scientists at PSL are working to characterize marine heatwaves, understand how they form and dissipate, and predict them in advance. On this page, we will provide current ocean maps, forecasts of heatwaves, interactive tools for users to explore ocean heatwaves themselves, links to research results and to webpages at other institutions.

#### The California Current Marine Heatwave Tracker - Blobtracker

Developed by oceanographers from NOAA Fisheries’ Southwest Fisheries Science Center as an experimental tool for natural resource managers, the California Current MHW Tracker is a program designed to understand, describe, and provide a historical context for the 2014-16 blob.2 It also produces a range of indices that could help forecast or predict future MHWs expected to impact our coast.