Counties Where Summer Heat Has Surged in the Last 50 Years

By Sam Stebbins  •  May 27, 2026
Woman relaxes on an orange float in the ocean.
Photo by Victor Rosario on Unsplash

Temperatures in the U.S. peak during the meteorological summer, a period that runs from the beginning of June through the end of August. According to the National Oceanic and Atmospheric Administration, summer temperatures averaged about 71.4°F over the course of the 20th century across the continental United States. In yet another sign of continuous atmospheric warming, average summer temperatures across the Lower 48 have exceeded the 20th century average nearly every year since 2001.

Notably, the months of winter, spring, and fall have also undergone meaningful warming trends in recent decades – and above-average temperatures during these seasons will have their own consequences, ecological and otherwise. When it comes to public health, however, hotter summers will have the most immediate and direct implications.

Using NOAA data, compiled by Climate Central, an independent, non-profit, research organization, Climate Crisis 247 identified the U.S. counties where summer temperatures climbed the most in the last half century. We reviewed the average change in annual summer temperatures, calculated using linear regression, for over 3,200 U.S. counties and county equivalents between 1970 and 2024. Only counties where average temperatures between June and August have climbed by at least 5°F since 1970 were included on this list. All supplemental temperature data is from NOAA, and population data are five-year estimates from the U.S. Census Bureau’s 2023 American Community Survey. Counties are listed in ascending order, based on their average change in annual summer temperatures since 1970.

The counties and independent cities on this list are confined to two states – New Mexico and Texas – and are collectively home to over 675,000 Americans.

11. Chaves County, New Mexico

  • Change in annual avg. summer temperatures, 1970-2024: +5.0°F
  • 20th century, baseline avg. summer temperature: 75.5°F
  • Average summer temperature by year: 81.3°F in 2024 (5.8°F warmer than baseline avg.), 75.3°F in 1970 (0.2°F cooler than baseline avg.)
  • Hottest summer on record: 2023, 81.9°F avg. temp. (6.4°F warmer than baseline avg.)
  • Local population: 64,446

10. Tom Green County, Texas

  • Change in annual avg. summer temperatures, 1970-2024: +5.0°F
  • 20th century, baseline avg. summer temperature: 81.7°F
  • Average summer temperature by year: 85.0°F in 2024 (3.3°F warmer than baseline avg.), 80.1°F in 1970 (1.6°F cooler than baseline avg.)
  • Hottest summer on record: 2011, 87.3°F avg. temp. (5.6°F warmer than baseline avg.)
  • Local population: 119,398

9. Menard County, Texas

  • Change in annual avg. summer temperatures, 1970-2024: +5.1°F
  • 20th century, baseline avg. summer temperature: 80.0°F
  • Average summer temperature by year: 83.1°F in 2024 (3.1°F warmer than baseline avg.), 78.8°F in 1970 (1.2°F cooler than baseline avg.)
  • Hottest summer on record: 2011, 86.0°F avg. temp. (6.0°F warmer than baseline avg.)
  • Local population: 1,964

8. Midland County, Texas

  • Change in annual avg. summer temperatures, 1970-2024: +5.1°F
  • 20th century, baseline avg. summer temperature: 80.9°F
  • Average summer temperature by year: 84.6°F in 2024 (3.7°F warmer than baseline avg.), 80.6°F in 1970 (0.3°F cooler than baseline avg.)
  • Hottest summer on record: 2011, 86.7°F avg. temp. (5.8°F warmer than baseline avg.)
  • Local population: 171,496
green tree on green grass field during sunset
Photo by David Banning on Unsplash

7. Loving County, Texas

  • Change in annual avg. summer temperatures, 1970-2024: +5.1°F
  • 20th century, baseline avg. summer temperature: 81.2°F
  • Average summer temperature by year: 85.9°F in 2024 (4.7°F warmer than baseline avg.), 80.7°F in 1970 (0.5°F cooler than baseline avg.)
  • Hottest summer on record: 2011, 88.1°F avg. temp. (6.9°F warmer than baseline avg.)
  • Local population: 54

6. Ward County, Texas

  • Change in annual avg. summer temperatures, 1970-2024: +5.1°F
  • 20th century, baseline avg. summer temperature: 82.2°F
  • Average summer temperature by year: 86.6°F in 2024 (4.4°F warmer than baseline avg.), 81.4°F in 1970 (0.8°F cooler than baseline avg.)
  • Hottest summer on record: 2011, 88.7°F avg. temp. (6.5°F warmer than baseline avg.)
  • Local population: 11,255

5. De Baca County, New Mexico

  • Change in annual avg. summer temperatures, 1970-2024: +5.2°F
  • 20th century, baseline avg. summer temperature: 75.1°F
  • Average summer temperature by year: 80.2°F in 2024 (5.1°F warmer than baseline avg.), 74.6°F in 1970 (0.5°F cooler than baseline avg.)
  • Hottest summer on record: 2020, 81.0°F avg. temp. (5.9°F warmer than baseline avg.)
  • Local population: 1,580

4. Lea County, New Mexico

  • Change in annual avg. summer temperatures, 1970-2024: +5.2°F
  • 20th century, baseline avg. summer temperature: 77.0°F
  • Average summer temperature by year: 81.9°F in 2024 (4.9°F warmer than baseline avg.), 76.6°F in 1970 (0.4°F cooler than baseline avg.)
  • Hottest summer on record: 2011, 84.3°F avg. temp. (7.3°F warmer than baseline avg.)
  • Local population: 73,154

3. Eddy County, New Mexico

  • Change in annual avg. summer temperatures, 1970-2024: +5.2°F
  • 20th century, baseline avg. summer temperature: 77.8°F
  • Average summer temperature by year: 83.2°F in 2024 (5.4°F warmer than baseline avg.), 77.5°F in 1970 (0.3°F cooler than baseline avg.)
  • Hottest summer on record: 2011, 84.5°F avg. temp. (6.7°F warmer than baseline avg.)
  • Local population: 61,114

2. Ector County, Texas

  • Change in annual avg. summer temperatures, 1970-2024: +5.2°F
  • 20th century, baseline avg. summer temperature: 80.5°F
  • Average summer temperature by year: 84.6°F in 2024 (4.1°F warmer than baseline avg.), 80.2°F in 1970 (0.3°F cooler than baseline avg.)
  • Hottest summer on record: 2011, 87.1°F avg. temp. (6.6°F warmer than baseline avg.)
  • Local population: 163,206

1. Winkler County, Texas

  • Change in annual avg. summer temperatures, 1970-2024: +5.2°F
  • 20th century, baseline avg. summer temperature: 81.0°F
  • Average summer temperature by year: 85.4°F in 2024 (4.4°F warmer than baseline avg.), 80.5°F in 1970 (0.5°F cooler than baseline avg.)
  • Hottest summer on record: 2011, 87.9°F avg. temp. (6.9°F warmer than baseline avg.)
  • Local population: 7,540


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