Global studies estimate about 550,000 heat-related deaths per year, and mortality linked to heat has risen sharply since the 1990s. In the U.S., recorded heat deaths are lower — JAMA reports about 21,518 deaths from 1999–2023 — but local data (notably Maricopa County’s 579 deaths in 2023) reveal concentrated risk where extreme heat and social vulnerability intersect. An analysis of 2018–2022 data ranks Arizona highest in heat-related deaths per 100,000; policymakers are urged to expand cooling centers, target outreach, and improve access to air conditioning to reduce future fatalities.
The U.S. States Where Heat Kills the Most People — Arizona Tops the List
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Extreme heat contributes to hundreds of thousands of deaths worldwide each year, but official counts understate the true toll because death certificates often list related causes (for example, cardiovascular disease) rather than heat itself. One widely cited analysis in The Lancet estimates roughly 550,000 heat-related deaths globally per year and reports that heat-related mortality rose about 63% since the 1990s, averaging roughly 546,000 annual deaths in 2012–2021.
In the United States the measured toll is lower but still serious. A JAMA analysis records 21,518 U.S. deaths attributed to heat from 1999 through 2023 — roughly 900 per year on average — though estimates vary by method and jurisdiction.
Local counts can differ sharply. Maricopa County, Arizona (which includes Phoenix), reported 579 heat-related deaths in 2023 and is frequently cited for its unusually detailed mortality tracking. As The Guardian observed, "There is no accurate nationwide heat death toll, and Maricopa County produces the country's most detailed heat mortality and morbidity information." Many victims were unhoused or lacked access to adequate air conditioning, highlighting socioeconomic drivers of risk.
Recent Heat Waves And Policy Challenges
Recent heat waves — including stretches when multiple heat domes raised temperatures above 100°F across large regions — broke records from New York City to Southern California. Such extreme events raise difficult public-health questions: local officials cannot feasibly check every home during prolonged heat, so many communities rely on public cooling centers (libraries, senior centers, community buildings) and targeted outreach to vulnerable populations.
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State Rankings And Key Metrics
Climatecrisis247 analyzed U.S. states using heat-related injury (HRI) deaths per 100,000 residents for the 2018–2022 study period, plus each state’s all-time maximum temperature and the average number of days per year with highs of 90°F or above. Georgetown University notes that risks of heat stroke rise substantially at sustained high temperatures; Phoenix commonly records more than 100 days per year above 100°F.
| Rank | State | HRI Deaths per 100k | All-Time Max Temp (°F) | Avg Days Above 90°F/yr |
|---|---|---|---|---|
| 1 | Arizona | 23.54 | 128 | 167 |
| 2 | Nevada | 19.81 | 125 | 109 |
| 3 | Arkansas | 2.94 | 120 | 65 |
| 4 | New Mexico | 2.85 | 122 | 75 |
| 5 | California | 1.48 | 134 | 62 |
| 6 | Oklahoma | 2.11 | 120 | 72 |
| 7 | Texas | 1.87 | 120 | 79 |
| 8 | Louisiana | 2.44 | 114 | 68 |
| 9 | Oregon | 3.93 | 119 | 14 |
| 10 | Kansas | 1.47 | 121 | 50 |
Data Sources And Limitations
Figures shown are based on the 2018–2022 study period. Primary sources include the CDC WONDER Underlying Cause of Death Database, NOAA NCEI Climate Extremes Records and 1991–2020 U.S. Climate Normals, and an analysis by Ladah Injury & Car Accident Lawyers. Important caveats: heat is often an indirect cause of death and can be underreported; jurisdictions use different methods to attribute deaths to heat; and socioeconomic factors (housing, cooling access, homelessness, occupation) strongly influence outcomes.
What Policymakers Can Do
As temperatures rise, officials can reduce harm by expanding cooling centers, offering targeted outreach to unhoused and low-income communities, subsidizing energy costs or air conditioning for vulnerable households, improving heat-health surveillance, and planning long-term mitigation such as urban cooling and resilient housing.
Bottom line: Heat-related deaths are rising globally and remain a preventable public-health risk in the U.S. where better data, targeted interventions, and attention to equity can save lives.
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