American Cities Where Extreme Heat Is Much More Common
Greenhouse gas emissions have surged across the world in the last century, and the impact these emissions have on the climate is becoming increasingly clear. The build up of carbon and methane pollution traps heat in the Earth’s atmosphere and ultimately results in higher temperatures. According to the World Meteorological Organization, each of the 10 hottest years on record have been in the last decade.
While a gradual, decades-long rise in average temperatures, often by fractions of a degree, may go unnoticed by most Americans, a sharp increase in the number of days marked by extreme heat is decidedly more apparent. In several U.S. cities, the number of extremely hot days in a given year has more than doubled since the 1970s and 1980s.
Using data from Climate Central, an independent, non-profit, research organization, Climate Crisis 247 identified the U.S. cities where the extreme heat has become much more common. We reviewed data on 90th percentile temperate, based on a 30-year average, for nearly 250 U.S. cities. For each city, we tallied the number of extremely hot days – those in which temperatures exceeded the 90th percentile – over three distinct time periods: 1971-1988, 1989-2006, and 2007-2024. Cities are ranked on the absolute difference in the number of extremely hot days reported between 2007 and 2024, and the number of days exceeding the same temperature threshold between 1971 and 1988. Only cities that reported at least 300 more extremely hot days between 2007 and 2024 than in the period from 1971 to 1988 were considered.
The 10 cities on this list are largely concentrated in the Western and Southern United States. Depending on the city, the 90th percentile temperature ranges from 79.9°F to 102.7°F – and the number of days temperatures exceeded that threshold since 2007 ranges from 403 to 787. Meanwhile, the number of extremely hot days reported in these same places from 1971 to 1988 only ranges from 82 to 197.
10. Grand Junction, Colorado
- 90th percentile temperature in city: 90.7°F
- Total days with temperatures exceeding 90th percentile; 2007-2024: 438 days
- Total days with temperatures exceeding 90th percentile; 1989-2006: 221 days
- Total days with temperatures exceeding 90th percentile; 1971-1988: 122 days
9. Odessa, Texas
- 90th percentile temperature in city: 96.3°F
- Total days with temperatures exceeding 90th percentile; 2007-2024: 433 days
- Total days with temperatures exceeding 90th percentile; 1989-2006: 246 days
- Total days with temperatures exceeding 90th percentile; 1971-1988: 106 days
8. San Angelo, Texas
- 90th percentile temperature in city: 96.4°F
- Total days with temperatures exceeding 90th percentile; 2007-2024: 431 days
- Total days with temperatures exceeding 90th percentile; 1989-2006: 225 days
- Total days with temperatures exceeding 90th percentile; 1971-1988: 89 days
7. Prescott, Arizona
- 90th percentile temperature in city: 91.0°F
- Total days with temperatures exceeding 90th percentile; 2007-2024: 493 days
- Total days with temperatures exceeding 90th percentile; 1989-2006: 264 days
- Total days with temperatures exceeding 90th percentile; 1971-1988: 145 days
6. Laredo, Texas
- 90th percentile temperature in city: 102.7°F
- Total days with temperatures exceeding 90th percentile; 2007-2024: 466 days
- Total days with temperatures exceeding 90th percentile; 1989-2006: 326 days
- Total days with temperatures exceeding 90th percentile; 1971-1988: 82 days
5. Fort Myers, Florida
- 90th percentile temperature in city: 90.0°F
- Total days with temperatures exceeding 90th percentile; 2007-2024: 540 days
- Total days with temperatures exceeding 90th percentile; 1989-2006: 259 days
- Total days with temperatures exceeding 90th percentile; 1971-1988: 156 days
4. Miami, Florida
- 90th percentile temperature in city: 86.4°F
- Total days with temperatures exceeding 90th percentile; 2007-2024: 645 days
- Total days with temperatures exceeding 90th percentile; 1989-2006: 284 days
- Total days with temperatures exceeding 90th percentile; 1971-1988: 181 days
3. San Juan, Puerto Rico
- 90th percentile temperature in city: 86.9°F
- Total days with temperatures exceeding 90th percentile; 2007-2024: 667 days
- Total days with temperatures exceeding 90th percentile; 1989-2006: 373 days
- Total days with temperatures exceeding 90th percentile; 1971-1988: 196 days
2. West Palm Beach, Florida
- 90th percentile temperature in city: 85.5°F
- Total days with temperatures exceeding 90th percentile; 2007-2024: 674 days
- Total days with temperatures exceeding 90th percentile; 1989-2006: 323 days
- Total days with temperatures exceeding 90th percentile; 1971-1988: 189 days
1. Honolulu, Hawaii
- 90th percentile temperature in city: 79.9°F
- Total days with temperatures exceeding 90th percentile; 2007-2024: 787 days
- Total days with temperatures exceeding 90th percentile; 1989-2006: 396 days
- Total days with temperatures exceeding 90th percentile; 1971-1988: 197 days
