Heat is the deadliest climate-related hazard in the U.S., and official counts likely understate its impact: the CDC reports about 1,700 annual heat deaths, while detailed investigations estimate the true toll may approach 9,000. Climate Central’s analysis (April–October, 2018–2025) found an average of 130 heat-related ER visits per day per 100,000 ER visits nationwide, with roughly 27% attributable to climate change. Regional rates vary widely—the Western and Southern Coastal and West South-Central regions have the highest averages—highlighting growing pressure on emergency care as temperatures rise.
U.S. Regions With the Highest Rates of Heat-Related ER Visits — Where Heat Is Straining Emergency Care
Photo by Ketut Subiyanto on Pexels
Heat is the deadliest climate-related hazard in the United States, and its impacts are increasing. Official tallies likely undercount heat’s true toll: the Centers for Disease Control and Prevention (CDC) reports about 1,700 heat-related deaths per year, while in-depth investigations by NPR and Boston University suggest the actual annual total may be closer to 9,000 when heat’s role in other fatalities is considered.
A broader view shows heat’s burden goes well beyond fatalities. Climate Central’s analysis for April–October, 2018–2025, found an average of 130 heat-related emergency department (ER) visits per day per 100,000 ER visits nationwide, and estimated that roughly 27% of those visits are attributable to climate change. However, regional impacts vary widely: in some parts of the country heat-related illness accounts for a much larger share of ER visits.
Below is a regional ranking based on Climate Central’s data (April–October, 2018–2025), compiled by Climate Crisis 247. Rankings reflect the average daily number of heat-related ER visits per 100,000 ER visits. Only U.S. states are listed for each region, though the underlying dataset may include some U.S. territories.
Regional Ranking (10 to 1)
10. Coastal Northeast
Average (Apr–Oct): 53 heat-related ER visits per 100,000 ER visits (≈41% attributable to climate change)
Worst day: June 24, 2025 — 1,429 per 100,000 (≈35% attributable to climate change)
Avg. regional temp that day: 95.0°F (estimated 93.2°F without climate change)
States: New Jersey, New York
9. New England
Average (Apr–Oct): 67 per 100,000 (≈37% attributable to climate change)
Worst day: June 24, 2025 — 2,011 per 100,000 (≈26% attributable to climate change)
Avg. regional temp that day: 95.5°F (estimated 93.9°F without climate change)
States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont
8. Mountain
Average (Apr–Oct): 84 per 100,000 (≈29% attributable to climate change)
Worst day: July 12, 2024 — 894 per 100,000 (≈33% attributable to climate change)
Avg. regional temp that day: 95.0°F (estimated 91.6°F without climate change)
States: Colorado, Montana, North Dakota, South Dakota, Utah, Wyoming
7. Upper Midwest
Average (Apr–Oct): 85 per 100,000 (≈30% attributable to climate change)
Worst day: June 22, 2025 — 1,396 per 100,000 (≈26% attributable to climate change)
Avg. regional temp that day: 91.8°F (estimated 90.3°F without climate change)
States: Illinois, Indiana, Michigan, Minnesota, Ohio, Wisconsin
6. Northwest
Average (Apr–Oct): 94 per 100,000 (≈35% attributable to climate change)
Worst day: June 28, 2021 — 6,763 per 100,000 (≈27% attributable to climate change)
Avg. regional temp that day: 98.8°F (estimated 96.8°F without climate change)
Photo byFlorian WehdeonUnsplash
States: Alaska, Idaho, Oregon, Washington
5. Mid-Atlantic
Average (Apr–Oct): 108 per 100,000 (≈33% attributable to climate change)
Worst day: June 24, 2025 — 1,828 per 100,000 (≈30% attributable to climate change)
Avg. regional temp that day: 96.4°F (estimated 94.6°F without climate change)
States: Delaware, Maryland, Pennsylvania, Virginia, West Virginia
4. Southeast
Average (Apr–Oct): 155 per 100,000 (≈25% attributable to climate change)
Worst day: June 25, 2025 — 1,185 per 100,000 (≈27% attributable to climate change)
Avg. regional temp that day: 92.8°F (estimated 91.0°F without climate change)
States: Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee
3. Central Midwest
Average (Apr–Oct): 199 per 100,000 (≈20% attributable to climate change)
Worst day: August 22, 2023 — 2,772 per 100,000 (≈19% attributable to climate change)
Avg. regional temp that day: 96.4°F (estimated 95.2°F without climate change)
States: Iowa, Kansas, Missouri, Nebraska
2. West South-Central
Average (Apr–Oct): 225 per 100,000 (≈25% attributable to climate change)
Worst day: June 27, 2023 — 1,256 per 100,000 (≈23% attributable to climate change)
Avg. regional temp that day: 98.1°F (estimated 96.3°F without climate change)
States: Arkansas, Louisiana, New Mexico, Oklahoma, Texas
1. Western and Southern Coastal
Average (Apr–Oct): 230 per 100,000 (≈23% attributable to climate change)
Worst day: July 22, 2023 — 1,605 per 100,000 (≈20% attributable to climate change)
Avg. regional temp that day: 92.3°F (estimated 90.5°F without climate change)
States: Arizona, California, Hawaii, Nevada
What This Means
These figures show wide geographic variation in heat’s effects on emergency care, driven by regional climate patterns, population vulnerability, and preparedness. Health systems, municipalities, and residents should plan for more frequent and severe heat events—by expanding cooling access, improving heat-health warning systems, protecting outdoor workers, and reducing greenhouse gas emissions to limit further warming.
Source: Climate Central analysis (April–October, 2018–2025), compiled by Climate Crisis 247. Photo credit: Florian Wehde / Unsplash.
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