The 24 Deadliest Heat Waves of the Last 10 Years

By Evan Comen • October 9, 2025

A red warning sign highlights extreme heat danger in a desert area.

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As climate change worsens, the frequency and severity of deadly heat waves continues to increase. More than 21,000 Americans have died due to heat-related causes since 1999, many during intense periods of abnormally high temperatures concentrated over a few days.

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Many of the deadliest heat waves occur in major metropolitan areas like Phoenix and Las Vegas, where older, high-risk Americans are more exposed to warm weather. And while global warming has unequivocally accelerated over the last century, the deadliest heat waves are rare, one-in-10,000-year events, such as the 118-degree heat dome in Portland in 2021, or the heat wave that killed 53 migrants stuck in an abandoned trailer in San Antonio in 2022. A closer look at NOAA data reveals the heat waves that caused the most deaths in the past decade.

To determine the deadliest heat waves of the last 10 years, Climate Crisis 247 reviewed data on storm event mortality from the NOAA. Heat wave events were ranked based on the total number of direct and indirect deaths that occurred due to abnormally high temperatures over a period of at least one day. Heat mortality reports are from county officials, official National Weather Service observations, and broadcast media. Supplemental data on maximum temperature is based on daily summaries from the NOAA’s National Centers for Environmental Information.

25. July 29-31, 2020 (Phoenix, AZ)

Photo by Nils Huenerfuerst on Unsplash

Official death toll: 15 deaths
Maximum temperature: 118°F
Population exposed: 1,609,000

24. August 24-28, 2020 (Phoenix, AZ)

Photo by Joe Cook on Unsplash

Official death toll: 16 deaths
Maximum temperature: 113°F
Population exposed: 1,609,000

23. June 8-12, 2022 (Phoenix, AZ)

Photo by Chris Tingom on Unsplash

Official death toll: 16 deaths

Maximum temperature: 114°F

Population exposed: 1,609,000

22. June 21-26, 2024 (Las Vegas, NV)

Photo by Grant Cai on Unsplash

Official death toll: 16 deaths
Maximum temperature: 112°F
Population exposed: 644,000

21. June 19-21, 2016 (Las Vegas, NV)

Photo by Leo_Visions on Unsplash

Official death toll: 17 deaths
Maximum temperature: 117°F
Population exposed: 644,000

20. July 24-28, 2018 (Las Vegas, NV)

Photo by Heather Gill on Unsplash

Official death toll: 17 deaths
Maximum temperature: 117°F
Population exposed: 644,000

19. June 17-25, 2017 (Las Vegas, NV)

Photo by Antonio Gabola on Unsplash

Official death toll: 18 deaths
Maximum temperature: 119°F
Population exposed: 644,000

18. August 1-5, 2018 (Las Vegas, NV)

Photo by Juliana Malta on Unsplash

Official death toll: 18 deaths
Maximum temperature: 112°F
Population exposed: 644,000

17. June 26-29, 2021 (Portland, OR)

Photo by Brandon DesJarlais on Unsplash

Official death toll: 18 deaths
Maximum temperature: 116°F
Population exposed: 646,000

16. June 5-8, 2024 (Las Vegas, NV)

Photo by Zachary DeBottis on Pexels

Official death toll: 19 deaths
Maximum temperature: 111°F
Population exposed: 644,000

15. July 6-8, 2017 (Las Vegas, NV)

Photo by Colon Freld on Pexels

Official death toll: 20 deaths
Maximum temperature: 118°F
Population exposed: 644,000

14. July 22-31, 2018 (Phoenix, AZ)

Photo by Matthew Jackson on Pexels

Official death toll: 20 deaths
Maximum temperature: 116°F
Population exposed: 1,609,000

13. July 9-11, 2021 (Phoenix, AZ)

Photo by Jeremy Alford on Pexels

Official death toll: 20 deaths
Maximum temperature: 112°F
Population exposed: 1,609,000

12. July 8-12, 2024 (Tucson, AZ)

Photo by JC Cervantes on Unsplash

Official death toll: 20 deaths
Maximum temperature: 111°F
Population exposed: 541,000

11. July 21-22, 2022 (Phoenix, AZ)

Photo by Gabriel Valdez on Unsplash

Official death toll: 21 deaths
Maximum temperature: 114°F
Population exposed: 1,609,000

10. July 22-29, 2016 (Las Vegas, NV)

Photo by marcwatson68 on Pixabay

Official death toll: 26 deaths
Maximum temperature: 117°F
Population exposed: 644,000

9. August 1-4, 2020 (Phoenix, AZ)

Photo by tmsims15 on Pixabay

Official death toll: 26 deaths
Maximum temperature: 114°F
Population exposed: 1,609,000

8. July 10-13, 2020 (Phoenix, AZ)

Photo by dcampbell11 on Pixabay

Official death toll: 32 deaths
Maximum temperature: 116°F
Population exposed: 1,609,000

7. July 20-25, 2024 (Las Vegas, NV)

Photo by 12019 on Pixabay

Official death toll: 34 deaths
Maximum temperature: 114°F
Population exposed: 644,000

6. June 12-20, 2021 (Phoenix, AZ)

Photo by meandcolors on Pixabay

Official death toll: 35 deaths
Maximum temperature: 118°F
Population exposed: 1,609,000

5. July 14-29, 2023 (Tucson, AZ)

Photo by Celtenator on Pixabay

Official death toll: 40 deaths
Maximum temperature: 112°F
Population exposed: 541,000

4. July 3-12, 2024 (Las Vegas, NV)

Photo by Christina on Unsplash

Official death toll: 42 deaths
Maximum temperature: 119°F
Population exposed: 644,000

3. August 12-20, 2020 (Phoenix, AZ)

Photo by Kenneth Lothridge on Unsplash

Official death toll: 43 deaths
Maximum temperature: 117°F
Population exposed: 1,609,000

2. June 27, 2022 (San Antonio, TX)

Photo by weston m on Unsplash

Official death toll: 53 deaths
Maximum temperature: 101°F
Population exposed: 1,445,000

1. June 26-29, 2021 (Portland, OR)

Photo by Adam Blank on Unsplash

Official death toll: 93 deaths
Maximum temperature: 116°F
Population exposed: 646,000

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