According to NOAA, the nine warmest years for the U.S. have all occurred since 2012, with the U.S. experiencing 23 billion-dollar weather and climate disasters in 2025, the third-highest number behind 2023 and 2024 tallies. As temperatures rise in the U.S. and periods of extreme heat become increasingly commonplace, the effects on drivers, vehicles, and road infrastructure become more pronounced.
Attorney Brian White Personal Injury Lawyers’ study will analyze how extreme heat affects U.S. state roads, including vehicle failures, deteriorating roads, and injury risks, to form the unique ‘America’s Hottest Roads: Heat-Related Driving Risk Index’. We also identify the states and regions where extreme heat creates the greatest dangers for motorists and often means they need to get in touch with a car accident lawyer.
Let’s start by taking a close look at the parts of America we consider especially high risk due to the rise of extreme heat conditions.
America’s Hottest Roads: The States Facing the Greatest Risk
Arizona is the number one state in our ‘America’s Hottest Roads: Heat-Related Driving Risk Index’ with a score of 88.83, followed by Louisiana (80.69) and Texas (79.68). (Houston provides a clear local example of why the index matters: recent periods of stunning heat that contributed to damaged freeways and necessitated emergency repairs.)
The index scores measure relative exposure and road vulnerability (not the probability that an individual driver will crash or suffer a breakdown), and combine sustained summer heat with traffic exposure and pavement condition to identify the states facing the greatest level of heat-related driving risk.
Arizona’s first-placed ranking is due to a number of factors: it recorded the nation’s highest average summer maximum temperature (95.79°F); it posted the most statewide days at or above 90°F (80); and it was the only state to feature a double-digit total of 100°F days (21).
Second-placed Texas recorded the second-highest average summer maximum (93.45°F), the second-highest number of 90°F days (78), and (along with Mississippi) shared the nation’s longest run of 90°F-plus weather (43 days).
Louisiana’s position above Texas illustrates why the index is valuable and confirms the fact that the ranking references much more than merely recording temperature levels. Louisiana’s score also reflects traffic exposure and pavement vulnerability, emphasizing the extent to which several risk factors can combine and compound driving issues. Florida’s top-five ranking is due to its 92.07°F average summer maximum, as well as 76 statewide 90°F days and a 35-day continuous heat run.
Here are the top 10 ranked states:
At the other end of the ranking, North Dakota placed last (13.56), followed by Minnesota (13.67) and Wyoming (18.56), reflecting their substantially lower sustained heat and traffic exposure.
Hot, Dangerous Pavement: How Heat Damages Roads
Extreme heat can cause roads to expand, warp, and buckle, especially if they’ve already been weakened by age, moisture, or years of being pummeled by heavy traffic. So while heat may be the triggering factor, the existing condition of the road determines its vulnerability.
The index treats pavement conditions as a discrete issue, separate from heat exposure. Rhode Island has the highest poor-pavement share (31.3%), followed by California (27%), Massachusetts (24.5%), New Jersey (18.5%), and New Mexico (18.2%). Despite Rhode Island ranking highest in this category, its 29th-placed overall ranking illustrates the fact that poor pavement alone does not create a high heat-risk score.
California represents the clearest overlap between high heat exposure and pavement vulnerability, appearing among both the five highest overall scores and the five largest poor-pavement shares. Louisiana’s 16.1% poor-pavement share (compared with Texas’s 7.3%) also helps explain why Louisiana ranks slightly higher overall despite Texas suffering stronger summer heat measures.
Houston provides a recent real-world example of the latter issue. During a two-week period of high temperatures, TxDOT reported damage to at least 10 Houston-area roadways, including an I-10 entrance ramp and Highway 6 near Alvin. A section of Highway 146 in Baytown also needed emergency overnight repairs.
Across Texas, TxDOT identified 788 roadway miles in its Laredo District as highly vulnerable to extreme heat, numbers that represent over half of the state’s high-vulnerability roadway miles. The agency cites rutting, buckling, cracking, temporary closures, detours, and disruptions to traffic systems as just some of the potential effects of warmer conditions.
And research augments these observations. A 2025 pavement study found modeled rut depth increased from 4 millimeters to 8 millimeters as pavement temperature rose from 34°C to 49°C, rising to about 13 millimeters at 63°C.
The Hot Vehicle Failures That Put Drivers at Risk
Heat affects drivers in ways that exceed road surface issues. High temperatures can also cause problems with batteries, cooling systems, and tires, while heavy traffic can make a breakdown more dangerous.
As part of our index, we measured traffic exposure by using vehicle miles traveled per lane-mile. By this count, New Jersey leads the rankings with 937,163, followed by Florida (891,656), California (821,885), Maryland (795,063), and Massachusetts (794,675).
Once again, it’s worth mentioning that no single-factor ranking necessarily dictates overall ranking: New Jersey ranks only No. 18 overall; traffic volume alone does not create a high heat-risk score.
Texas’s 436,026 VMT per lane-mile count means its elevated overall ranking is driven more by sustained summer heat as opposed to the state being among the nation’s busiest road networks.
AAA received more than 27 million emergency roadside calls in 2024. Around 13 million involved towing, while 7 million were due to battery problems (combined, both types of call accounted for roughly 74% of all calls).
AAA identifies dead batteries, engine trouble, and flat tires as the vehicle problems most likely to disrupt summer travel, with heat a key factor when it comes to battery degradation and cooling-system strain.
Tires are another significant issue. In 2024, NHTSA reported 511 deaths due to tire-related crashes. Despite those fatalities not being classified as heat-specific, NHTSA warns that sustained high temperatures can accelerate the deterioration of tires and contribute to blowouts or tread separation.
Extreme heat can also compromise vehicle efficiency. AAA testing found that operating at 95°F reduced battery-electric vehicle efficiency by 10.4% and range by 8.5% (compared with a 75°F baseline); hybrid fuel economy also dropped by 12%.
When Heat and Breakdowns Become Safety Emergencies
Heat-related road and vehicle problems can quickly develop into serious safety emergencies.
A 2026 study of more than 1.4 million crashes across 177 California cities found that, at the 99th temperature percentile, the relative risk increased to 1.35 for severe crashes and 1.22 for fatal crashes.
The study found especially elevated risks for vulnerable road users (including bicycle- and pedestrian-involved crashes) and a more pronounced heat-risk gradient at intersections compared to other road environments.
(While these findings suggest a statistical association between extreme temperatures and crash severity, they don’t prove that heat caused any specific collision.)
Breakdowns create another risk. AAA Foundation research found that more than 2,100 people were killed on the roadside outside their broken-down disabled vehicle between 2019 and 2023. While these deaths were not heat-specific, they do illustrate how a vehicle failure can become dangerous if occupants are forced onto or adjacent to an active road.
Extreme pavement temperatures create a separate injury risk. From June to August 2023, Arizona’s Valleywise Health burn center dealt with 136 patients suffering from severe pavement-contact burns.
Fourteen of the patients died, 34% needed intensive care treatment, and many needed skin grafts or multiple surgeries following contact with extremely hot pavement.
The Cost of Extreme Heat on Drivers and Transport Systems
The financial consequences of extreme heat on roads go well beyond vehicle repair costs.
The index’s top 10 states averaged 63.8 statewide 90°F days, compared with 4.5 among the bottom 10. They also averaged 443,614 VMT per lane-mile, over twice the 197,252 average among the bottom 10.
For drivers, heat can mean an increase in operating costs. AAA found that driving at 95°F added around $6.78 per 1,000 miles for a home-charged electric vehicle, $16.25 to commercial charging costs, and $13.02 to hybrid costs. AAA’s 2025 driving-cost study estimates maintenance, repair, and tires at 11.04 cents per mile for a new vehicle, about $8,280 across its five-year, 75,000-mile ownership model before heat-related repairs are factored in.
Crashes carry much higher costs. The National Safety Council estimates the 2024 economic cost of a property-damage-only crash at about $6,600 per damaged vehicle, while a disabling injury costs about $174,000, and a motor-vehicle death costs around $2.05 million. These are national crash-cost estimates as opposed to heat-only figures.
A U.S. study suggested that there’s a 3.4% increase in fatal traffic crashes on heat–wave days compared with comparable non–heat–wave days
Public infrastructure also faces growing costs. A national pavement study projected that rising temperatures could add about $19 billion in U.S. pavement costs by 2040 under a moderate warming scenario; under a higher warming scenario, those costs rise to $26.3 billion.
The federal PROTECT program provides $8.7 billion over five years for transportation projects designed to improve their resilience to extreme weather and climate hazards.
Heat and Preparing For Hotter Futures
America’s Hottest Roads index shows that the greatest heat-related driving risk occurs where sustained extreme temperatures overlap with heavy road use or existing pavement vulnerability.
Arizona ranks No. 1 because it combines the country’s most persistent summer heat with substantial road exposure; Louisiana and Texas follow closely for different combinations of those risk factors.
For Texas drivers, Houston’s recent heat-damaged freeways illustrate why the index matters: as extreme heat becomes more common, roads and vehicles increasingly face stresses that can turn ordinary travel into a safety challenge.
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Index Methodology
America’s Hottest Roads: Heat-Related Driving Risk Index
| Index measure | Weight | What it represents |
| Average summer maximum temperature | 20% | Overall, June-August daytime heat exposure |
| Statewide days at or above 90°F | 20% | Frequency of sustained high-temperature days |
| Statewide days at or above 100°F | 15% | Most extreme statewide heat exposure |
| Longest continuous 90°F-plus run | 15% | Duration of uninterrupted heat |
| VMT per lane-mile | 15% | Traffic exposure on the available road network |
| Poor pavement share | 15% | Existing roadway vulnerability |
The index ranks the contiguous 48 states using June-August 2025 NOAA climate data and FHWA Highway Statistics 2024 road data. Each measure was converted to a 0-100 state-percentile score, weighted, and ultimately combined to form a final index score.
Poor pavement represents reported arterial mileage with an International Roughness Index above 170 inches per mile. Alaska and Hawaii were not ranked because equivalent finalized NOAA daily statewide grid data were not available for the relevant climate measures.
The scores represent relative exposure and vulnerability. They are not crash probabilities and don’t prove that heat caused an individual crash, breakdown, or pavement failure.
Road-surface temperatures did not form part of the study as there was no available standardized observed statewide dataset for every state.
Data sources
Heat waves and fatal traffic crashes in the continental United States – ScienceDirect
https://www.fhwa.dot.gov/policyinformation/statistics/2024/xls/vm2.xlsx
https://www.fhwa.dot.gov/pavement/concrete/pubs/hif23006.pdf
AAA Urges Drivers to Stay Proactive on Auto Repair and Maintenance
Understanding the Circumstances of Roadside Fatalities – AAA Foundation for Traffic Safety
Climate Change Is Subjecting More Americans to Unbearable Extreme Heat
Summer Heat Waves Are Pushing Older Car Repair Bills to $8,000 – Gadget Review