Climate Change Indicators: Heat Waves
This indicator describes trends in multi-day extreme heat events across the United States.
graph figureFigure 1. Heat Wave Characteristics by Decade
map figureFigure 2. Heat Wave Characteristics in Cities
graph figureFigure 3. Heat Wave Index
Figure 1. Heat Wave Characteristics in the United States by Decade, 1961–2023
Set of four graphs that show decadal averages from the 1960s through the 2020s for four characteristics of heat waves: the number that occur each year, their duration in number of days, the length of the annual heat wave season in days, and the intensity in terms of degrees above the heat wave temperature threshold.
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This figure shows changes in the number of heat waves per year (frequency); the average length of heat waves in days (duration); the number of days between the first and last heat wave of the year (season length); and how hot the heat waves were, compared with the local temperature threshold for defining a heat wave (intensity). These data were analyzed from 1961 to 2023 for 50 large metropolitan areas. The graphs show averages across all 50 metropolitan areas by decade.
Data source: NOAA, 20246
Web update: June 2024
Key Points | Background | About the Indicator | About the Data | Technical Documentation
Key Points
https://www.epa.gov/climate-indicators/climate-change-indicators-heat-waves
