The most dangerous summer heat in America is concentrated across the South and Sun Belt, where a combination of scorching daytime temperatures, warm nights and vulnerable populations is creating increasingly difficult conditions for residents.
A nationwide analysis from Texas Law Dog ranks Florida as the state facing the greatest overall summer heat danger, giving it a Heat-Danger Index score of 84.5 out of 100. Arizona follows by the narrowest of margins at 84.4, Louisiana ranks third at 84.0 and Texas places fourth at 81.7.
The study compared all 50 states using both immediate and long-term temperature conditions, including average summer maximum and minimum temperatures, five-year heat patterns and how unusual 2025 temperatures were compared with historical conditions. It also incorporated the proportion of residents who may be especially vulnerable to extreme heat.
The result shows that the states experiencing the hottest days are not always the same states experiencing the greatest overall heat danger.
The 10 States Facing the Greatest Summer Heat Risk
All 10 states at the top of Texas Law Dog’s Heat-Danger Index are located in the South or Sun Belt, demonstrating how heavily the country’s most sustained summer heat remains concentrated across the region.
| Rank | State |
|---|---|
| 1 | Florida |
| 2 | Arizona |
| 3 | Louisiana |
| 4 | Texas |
| 5 | Mississippi |
| 6 | Arkansas |
| 7 | Oklahoma |
| 8 | Alabama |
| 9 | South Carolina |
| 10 | Georgia |
Florida’s No. 1 position is driven in part by how little temperatures fall after sunset. Its average summer minimum temperature reached 73.8°F, giving residents less overnight relief following high daytime temperatures.
Arizona presents a different pattern. The state had the highest average daytime summer temperature in the country at 95.7°F. Its grid cells also averaged 33.5 summer days reaching at least 100°F and 6.2 days reaching at least 110°F, the most extreme figures included in the study.
Texas, meanwhile, stands out for persistence. Its average summer maximum temperature across the five summers from 2021 through 2025 was 95.2°F, the highest five-year average in the nation.
Those differences demonstrate why a heat ranking based solely on the single hottest temperature would tell only part of the story. Repeated hot days, warm nights and prolonged exposure can combine to create a more sustained threat.
Extreme Heat Is Reaching More Americans
The state rankings are unfolding against a broader pattern of unusually high temperatures.
Texas Law Dog reports that 2025 was the fourth-warmest year in 131 years of records across the contiguous United States. The nationwide annual average temperature reached 54.6°F, or 2.6°F above the 20th-century average. July averaged 75.4°F, 1.8°F above its historical norm.
The following year brought another widespread summer heat event. During July 2026, extreme heat warnings affected 23 states, with an estimated 165 million people exposed to major or extreme heat risk and temperatures reaching as high as 115°F.
Some states are also experiencing increasingly unusual nighttime heat.
Twelve states, including Alabama, Georgia and West Virginia, recorded their warmest average July minimum temperatures in 2025. North Carolina had its second-warmest July on record, while Georgia, West Virginia and Maryland recorded their third-warmest July periods.
Those nighttime temperatures matter because residents have less opportunity to recover from the heat before another hot day begins.
Heat Waves Are Becoming More Frequent and Lasting Longer
Extreme temperatures are no longer limited to isolated record-setting afternoons.
The Texas Law Dog study reports that major U.S. cities now experience about six heat waves per year, compared with roughly two annually during the 1960s. The urban heat-wave season has expanded to approximately 46 days, while an individual heat wave now lasts around four days on average.
Humidity can make already dangerous temperatures feel substantially hotter. At 95°F with 50% humidity, the apparent temperature can reach approximately 107°F. Exposure to direct sunlight can push the apparent temperature even higher.
That combination means the thermometer alone does not necessarily describe the full level of exposure people face outdoors.
Hot-Car Deaths Are Concentrated in High-Heat States
One of the study’s clearest findings involves children who die after being trapped in hot vehicles.
Between 1998 and 2025, the 10 states at the top of the Heat-Danger Index accounted for 531 of 1,038 reported child hot-car deaths nationwide, or 51.2% of the total. The five highest-ranked heat states alone accounted for 378 deaths.
| Heat-Risk Rank | State | Child Hot-Car Deaths, 1998-2025 |
|---|---|---|
| 1 | Florida | 115 |
| 2 | Arizona | 46 |
| 3 | Louisiana | 39 |
| 4 | Texas | 155 |
| 5 | Mississippi | 23 |
| 6 | Arkansas | 20 |
| 7 | Oklahoma | 31 |
| 8 | Alabama | 34 |
| 9 | South Carolina | 25 |
| 10 | Georgia | 43 |
Texas recorded the largest raw total among those states, with 155 deaths.
When adjusted for the population of children age 14 and younger, the difference between hotter and cooler states becomes even more pronounced. The 10 highest-ranked heat states averaged 33.7 hot-car deaths per 1 million children, compared with 8 per 1 million among the 10 lowest-ranked states. That makes the average rate in the highest-risk group more than four times greater.
The vehicle itself intensifies the danger. A car can reach approximately 117°F within an hour when the outside temperature is just 72°F, and about 80% of the interior temperature increase occurs during the first 30 minutes.
Children younger than 2 account for 54% of child hot-car deaths, with the average victim approximately 27 months old.
Heat-Related Illness Sends Thousands to Emergency Departments
The health burden extends well beyond hot vehicles.
The study identifies 119,605 heat-related emergency department visits in 2023, with 92% occurring between May and September. During July and August, the rate reached an average of 303 heat-related visits for every 100,000 emergency department visits, compared with 97 per 100,000 during May, June and September.
Men recorded more than twice the heat-related emergency visit rate of women, at 271 versus 104 per 100,000 visits.
Geography also produced a sharp divide. Arkansas, Louisiana, New Mexico, Oklahoma and Texas recorded rates nearly 10 times those seen in New York and New Jersey.
The findings indicate that the same states dealing with persistent high temperatures are also carrying a disproportionate burden of heat illness.
Outdoor Workers Face Another Layer of Exposure
The risk is particularly significant for people whose jobs require them to remain outside during the hottest part of the day.
There were 48 occupational heat deaths in 2024, according to federal figures incorporated into Texas Law Dog’s analysis. Forty occurred outdoors, and construction workers accounted for half of the total, with 24 deaths.
Longer-term statistics show the problem is not confined to a single summer. Between 1992 and 2022, 1,042 worker heat deaths were recorded nationally. Nearly 34,000 heat illnesses resulted in time away from work between 2011 and 2020.
The study identifies Arkansas, Oklahoma, Louisiana, Texas, Illinois and Arizona among states with particularly high documented construction-worker heat fatality rates.
Population exposure also varies. Wyoming has the country’s highest share of outdoor workers at 14.4%, while South Dakota receives the highest overall population-vulnerability score in the index at 76.2 despite ranking only 30th for total heat danger.
Extreme Heat Can Also Create Problems for Drivers
High temperatures can affect vehicles and road infrastructure long before a driver shows symptoms of heat illness.
According to information incorporated into the Texas Law Dog analysis, pavement temperatures can climb to approximately 150°F, increasing the risk of tire deterioration and blowouts. Sustained high temperatures can also significantly shorten the useful life of vehicle batteries.
Texas provides a particularly important example.
A 2025 state transportation-resilience assessment found that more than half of Texas roadways had moderate or high vulnerability to extreme heat and wildfire. Among the potential effects identified were pavement rutting, buckling and cracking.
The danger can compound during a breakdown. A tire failure or battery problem that might normally be an inconvenience can leave a motorist stranded on the roadside during triple-digit temperatures.
High Temperatures Are Also Testing the Power Grid
Air conditioning becomes a critical health safeguard during prolonged heat, but widespread cooling demand puts enormous pressure on electricity systems.
Texas reached a record electricity-demand level of 91,089 megawatts on July 22, 2026, surpassing its previous August 2023 record of 85,508 megawatts by 6.5%.
Demand climbed rapidly during the summer, increasing from 77,822 megawatts on May 29 to more than 91,000 megawatts by late July.
At the household level, power reliability can become a health issue when high temperatures persist through the night and air conditioning is unavailable.
Yet electricity reliability does not perfectly align with temperature rankings. Among the 10 highest-risk heat states, South Carolina recorded the greatest 2024 outage duration when major events were included, while Arizona recorded the lowest.
How Texas Law Dog Created the Heat-Danger Index
Texas Law Dog constructed its index using five measures, with physical heat conditions accounting for 80% of the final score and population vulnerability accounting for 20%.
| Component | Weight |
|---|---|
| 2025 average summer maximum temperature | 30% |
| 2025 average summer minimum temperature | 20% |
| 2021-2025 average summer maximum temperature | 20% |
| 2025 maximum-temperature anomaly | 10% |
| Population vulnerability | 20% |
The vulnerability component incorporates the proportion of children under 5, adults age 65 and older and workers employed in natural resources, construction and maintenance occupations.
Texas Law Dog converted each measure to a state-relative percentile before combining the components into the final 0-to-100 score. Additional measures, including days at or above 90°F, 100°F and 110°F and historical child hot-car deaths, were used for context but did not affect the final ranking.
The index therefore does not predict how many deaths, illnesses, outages or crashes a state will experience. Instead, it shows where several conditions associated with dangerous summer heat overlap most strongly.
The findings put Florida, Arizona, Louisiana and Texas at the center of America’s summer heat problem, but they also show that extreme heat takes different forms from state to state. Florida’s danger is amplified by warm nights, Arizona experiences the country’s most intense daytime temperatures and Texas combines exceptionally persistent heat with major exposure for drivers, infrastructure and outdoor workers.
As hot conditions become more frequent and last longer, the data suggest that summer heat is no longer simply a weather story. It is increasingly a transportation, workplace, health and public-safety issue.
