By 2100, Cities Where Daily Summer Temps Will be 100 Degrees or More

The climate change era is, so far, largely defined by an unprecedented warming trend. According to researchers at NASA, global temperatures are rising 10 times faster than they would have at similar points in previous climate cycles over the last 800,000 years. While temperatures in the United States are not rising as fast as in other parts of the world, the changes are still palpable – particularly in some of America’s hottest cities. 

In Phoenix, Arizona, for example, temperatures exceeded 100°F on 100 or more days in all but one of the last 25 years. Meanwhile, over the 25 year period ending in 1975, there were only seven years with at least 100 days of triple-digit temperatures in Phoenix. As of 2025, Phoenix, along with Las Vegas, Nevada, and Yuma, Arizona, is one of only a handful U.S. cities where average daily highs during the summer months exceed 100°F, according to the National Oceanic and Atmospheric Administration. 

Notably, however, the list of cities where 100-plus degree summer heat is the norm will likely get considerably longer in the coming decades. A recent report from the non-profit research and advocacy group Climate Central examined average summer temperatures in 243 places across the United States and found that all but seven of them have gotten hotter since 1970 – in most cases by over 2°F. If this rate of warming does not slow, daily highs of at least 100°F will become routine by the end of the 21st century in multiple U.S. cities. 

Using data from Climate Central and NOAA, Climate Crisis 247 identified the U.S. cities where triple-digit summer temperatures will be a daily occurrence by the year 2100. We ranked all 152 cities with available data from both sources on the projected average daily high during the summer season by the end of the century. Calculations were made using local average annual rates of warming between 1975 and 2025 and applying that rate to average local temperatures in the summer of 2025. Only cities where average daily summer highs are not already 100°F or more are listed. All cities with projected daily highs of at least 99.5°F or higher between the beginning of June and the end of August are listed. 

10. Medford, Oregon

Projected summer temperatures by 2100: 99.7°F daily high; 83.3°F daily average

Summer temperatures in 2025: 92.2°F daily high; 75.8°F daily average

Increase in average summer temperature, 1975-2025: +5.5°F (+4.1°F linked to human-caused climate change)

City population: 86,315

9. Houston, Texas

Projected summer temperatures by 2100: 99.7°F daily high; 92.2°F daily average

Summer temperatures in 2025: 93.3°F daily high; 85.8°F daily average

Increase in average summer temperature, 1975-2025: +4.7°F (+2.6°F linked to human-caused climate change)

City population: 2,328,253

8. Bakersfield, California

Projected summer temperatures by 2100: 100.0°F daily high; 86.3°F daily average

Summer temperatures in 2025: 97.1°F daily high; 83.4°F daily average

Increase in average summer temperature, 1975-2025: +2.1°F (+4.3°F linked to human-caused climate change)

City population: 411,986

7. Salt Lake City, Utah

Projected summer temperatures by 2100: 100.0°F daily high; 87.4°F daily average

Summer temperatures in 2025: 91.8°F daily high; 79.2°F daily average

Increase in average summer temperature, 1975-2025: +6.0°F (+6.1°F linked to human-caused climate change)

City population: 208,007

6. San Antonio, Texas

Projected summer temperatures by 2100: 100.6°F daily high; 90.5°F daily average

Summer temperatures in 2025: 95.1°F daily high; 85.0°F daily average

Increase in average summer temperature, 1975-2025: +4.0°F (+2.5°F linked to human-caused climate change)

City population: 1,479,835

5. Shreveport, Louisiana

Projected summer temperatures by 2100: 101.2°F daily high; 91.1°F daily average

Summer temperatures in 2025: 95.3°F daily high; 85.2°F daily average

Increase in average summer temperature, 1975-2025: +4.3°F (+2.7°F linked to human-caused climate change)

City population: 180,982

4. Austin, Texas

Projected summer temperatures by 2100: 102.0°F daily high; 91.6°F daily average

Summer temperatures in 2025: 95.7°F daily high; 85.3°F daily average

Increase in average summer temperature, 1975-2025: +4.6°F (+2.7°F linked to human-caused climate change)

City population: 979,539

3. Fresno, California

Projected summer temperatures by 2100: 103.9°F daily high; 88.8°F daily average

Summer temperatures in 2025: 97.1°F daily high; 82.0°F daily average

Increase in average summer temperature, 1975-2025: +5.0°F (+6.8°F linked to human-caused climate change)

City population: 545,970

2. El Paso, Texas

Projected summer temperatures by 2100: 106.6°F daily high; 94.5°F daily average

Summer temperatures in 2025: 98.0°F daily high; 85.9°F daily average

Increase in average summer temperature, 1975-2025: +6.3°F (+4.3°F linked to human-caused climate change)

City population: 680,130

1. Reno, Nevada

Projected summer temperatures by 2100: 107.5°F daily high; 90.9°F daily average

Summer temperatures in 2025: 92.1°F daily high; 75.5°F daily average

Increase in average summer temperature, 1975-2025: +11.3°F (+5.1°F linked to human-caused climate change)

City population: 273,212