The 10 Counties Where the Most People Die From Heat
This summer has seen several major heat domes that have shattered temperature records and exposed millions of Americans to 100°F temperatures for the first time. All of the 10 hottest years on record have occurred since 2010, and in July the average temperature in the contiguous United States was 75.4°F, exceeding climate normals by 1.8°F.
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Extreme heat is becoming harder to ignore, and is exacting a larger human toll every year. Hundreds of Americans die from heat exposure annually, and thousands are sent to the emergency room for heat-related illness. While heat deaths are not tallied uniformly from county to county, a look at CDC mortality data reveals the places where the most Americans die from heat exposure every year.
To determine the counties where the most people die due to excessive heat, Climate Crisis 247 reviewed data on mortality from the Centers for Disease Control and Prevention’s WONDER database. Counties were ranked based on the total number of reported deaths due exposure to excessive natural heat (hyperthermia) from 2018 to 2013. Supplemental data on average daily maximum temperature are from NOAA’s National Centers for Environmental Information. Population data is from the U.S. Census Bureau.
10. Dallas County, TX
- Mortality due to excessive heat, 2018-2023: 60 deaths
- Excessive heat mortality rate: 0.4 deaths per 100,000 residents
- Average summer daily high, 2024: 85.0°F
- Total population: 2,603,816
- County seat: Dallas
9. Riverside County, CA
- Mortality due to excessive heat, 2018-2023: 66 deaths
- Excessive heat mortality rate: 0.4 deaths per 100,000 residents
- Average summer daily high, 2024: 88.7°F
- Total population: 2,449,909
- County seat: Riverside
8. Yuma County, AZ
- Mortality due to excessive heat, 2018-2023: 66 deaths
- Excessive heat mortality rate: 5.2 deaths per 100,000 residents
- Average summer daily high, 2024: 94.0°F
- Total population: 207,685
- County seat: Yuma
7. Multnomah County, OR
- Mortality due to excessive heat, 2018-2023: 85 deaths
- Excessive heat mortality rate: 1.8 deaths per 100,000 residents
- Average summer daily high, 2024: 66.2°F
- Total population: 803,863
- County seat: Portland
6. Harris County, TX
- Mortality due to excessive heat, 2018-2023: 89 deaths
- Excessive heat mortality rate: 0.3 deaths per 100,000 residents
- Average summer daily high, 2024: 84.6°F
- Total population: 4,758,579
- County seat: Houston
5. Tarrant County, TX
- Mortality due to excessive heat, 2018-2023: 89 deaths
- Excessive heat mortality rate: 0.7 deaths per 100,000 residents
- Average summer daily high, 2024: 85.2°F
- Total population: 2,135,743
- County seat: Fort Worth
4. Pima County, AZ
- Mortality due to excessive heat, 2018-2023: 113 deaths
- Excessive heat mortality rate: 1.8 deaths per 100,000 residents
- Average summer daily high, 2024: 87.2°F
- Total population: 1,049,947
- County seat: Tucson
3. Mohave County, AZ
- Mortality due to excessive heat, 2018-2023: 239 deaths
- Excessive heat mortality rate: 18.4 deaths per 100,000 residents
- Average summer daily high, 2024: 85.7°F
- Total population: 217,420
- County seat: Kingman
2. Clark County, NV
- Mortality due to excessive heat, 2018-2023: 391 deaths
- Excessive heat mortality rate: 2.8 deaths per 100,000 residents
- Average summer daily high, 2024: 88.6°F
- Total population: 2,293,764
- County seat: Las Vegas
1. Maricopa County, AZ
- Mortality due to excessive heat, 2018-2023: 648 deaths
- Excessive heat mortality rate: 2.4 deaths per 100,000 residents
- Average summer daily high, 2024: 92.5°F
- Total population: 4,491,987
- County seat: Phoenix