Extreme Summer Heat Is Putting U.S. Roads, Cars and Drivers Under Greater Strain

America’s hottest states are facing a transportation challenge that extends far beyond uncomfortable temperatures.

Prolonged summer heat can weaken pavement, increase stress on tires and batteries, reduce vehicle efficiency and expose motorists to dangerous roadside conditions when breakdowns occur. Research has also found associations between extreme temperatures and more severe traffic crashes.

A nationwide analysis by Attorney Brian White examined where those risks overlap most heavily, comparing states across summer temperatures, prolonged periods of extreme heat, traffic exposure and pavement condition.

The findings place Arizona at the top of the country for heat-related driving risk, with an overall score of 88.83 out of 100. Louisiana follows at 80.69, while Texas ranks third at 79.68.

The results show that the states facing the most difficult summer driving environments are not necessarily those with the hottest temperatures alone. Poor pavement, road usage and the duration of extreme heat can substantially change the overall risk picture.

Arizona Experiences the Most Intense Heat Conditions

Arizona’s position at the top of the ranking is largely explained by the intensity and persistence of its summer temperatures.

The state recorded an average summer maximum temperature of 95.79°F, the highest of any state included in the analysis.

Arizona also experienced:

• 80 statewide days at or above 90°F
• 21 statewide days at or above 100°F
• The most 90°F days in the country
• The only double-digit statewide total of 100°F days

Those conditions create prolonged periods in which road surfaces and vehicles are repeatedly exposed to extreme temperatures.

Texas had the country’s second-highest average summer maximum at 93.45°F and recorded 78 statewide days at or above 90°F.

Texas and Mississippi also shared the country’s longest uninterrupted stretch of 90°F-or-hotter weather, at 43 consecutive days.

Florida experienced similarly persistent heat, with 76 days at or above 90°F and a 35-day continuous stretch of temperatures reaching that threshold.

State	Key Summer Heat Finding
Arizona	95.79°F average summer maximum; 80 days at 90°F+
Texas	93.45°F average maximum; 78 days at 90°F+
Mississippi	43-day continuous stretch at 90°F+
Florida	76 days at 90°F+; 35-day continuous stretch

Attorney Brian White’s analysis suggests these prolonged stretches matter because they continually expose pavement, vehicles and drivers to high-temperature conditions rather than limiting the problem to isolated record-breaking days.

Louisiana Shows Why Heat Alone Does Not Determine Road Risk

Louisiana’s second-place ranking is particularly revealing.

The state did not record temperatures as extreme as Arizona or Texas, yet it finished ahead of Texas in the combined ranking because heat coincides with weaker pavement conditions.

Approximately 16.1% of Louisiana’s arterial pavement was classified as being in poor condition, more than double the 7.3% recorded in Texas.

That combination can increase infrastructure vulnerability as pavement expands and softens under high temperatures.

Nationally, the states with the largest shares of poor pavement were:

State	Arterial Pavement Rated Poor
Rhode Island	31.3%
California	27.0%
Massachusetts	24.5%
New Jersey	18.5%
New Mexico	18.2%

Rhode Island’s poor pavement did not translate into a high overall heat-risk ranking because its temperatures are substantially more moderate. It finished 29th overall.

California presents a different concern because significant pavement deficiencies overlap with much warmer conditions.

Research cited in Attorney Brian White’s analysis also indicates that pavement deformation accelerates as temperatures climb.

One 2025 study modeled pavement rut depth at approximately 4 millimeters when temperatures reached 34°C, increasing to 8 millimeters at 49°C and roughly 13 millimeters at 63°C.

That relationship helps illustrate why sustained heat can become an infrastructure problem rather than simply a weather concern.

Extreme Heat Has Already Damaged Texas Roads

Evidence of heat-related road problems has already emerged in major metropolitan areas.

During one two-week period of high temperatures, the Texas Department of Transportation reported heat-related damage affecting at least 10 roadways around Houston.

Incidents included damage to an Interstate 10 entrance ramp, Highway 6 near Alvin and Highway 146 in Baytown, where emergency overnight repairs were required.

Elsewhere in Texas, transportation officials identified 788 roadway miles in the Laredo District as highly vulnerable to extreme heat.

That represented more than half of all Texas road mileage classified in the highest heat-vulnerability category included in the research.

Extreme heat can contribute to several forms of pavement distress, including:

• Rutting
• Cracking
• Buckling
• Surface deformation
• Emergency lane closures and repairs

Those disruptions can create additional hazards by altering traffic patterns, producing sudden lane changes or forcing motorists onto detours.

Some of America’s Most Heavily Used Roads Also Face Extreme Heat

Traffic volume adds another dimension to the problem.

Attorney Brian White compared states using vehicle miles traveled per lane-mile, a measure designed to capture how intensely road networks are used.

New Jersey recorded the country’s highest traffic exposure at 937,163 vehicle miles traveled per lane-mile.

Florida ranked second at 891,656, followed by California at 821,885.

State	Vehicle Miles Traveled per Lane-Mile
New Jersey	937,163
Florida	891,656
California	821,885
Maryland	795,063
Massachusetts	794,675

New Jersey ranked only 18th in the combined heat-risk index because it experiences less severe summer heat than states across the South and Southwest.

Florida and California, however, combine substantial traffic exposure with much hotter conditions.

Texas recorded 436,026 vehicle miles traveled per lane-mile, meaning its high overall ranking is driven more heavily by extreme temperatures and prolonged heat than by unusually concentrated road use.

High Temperatures Put Vehicle Components Under Additional Stress

Drivers do not need to encounter visibly damaged pavement to experience the effects of extreme heat.

Vehicle batteries, tires and cooling systems can all be affected by sustained high temperatures.

AAA handled more than 27 million roadside assistance calls during 2024, including approximately:

• 13 million towing calls
• 7 million battery-related calls

Together, towing and battery problems accounted for roughly 74% of all roadside assistance calls.

The figures do not indicate that extreme heat caused every incident. They do, however, illustrate how frequently motorists experience the types of mechanical problems that high temperatures can aggravate.

Tires provide another example.

The National Highway Traffic Safety Administration recorded 511 deaths in tire-related crashes during 2024.

Those crashes were not necessarily heat-related, but sustained high temperatures can accelerate tire deterioration and increase the risk of pressure problems, tread separation and blowouts.

Driving at 95°F Can Reduce Vehicle Efficiency

Even properly functioning vehicles can operate less efficiently in extreme heat.

AAA testing cited in the Attorney Brian White analysis compared vehicle performance at 95°F with performance at 75°F.

For battery-electric vehicles, the hotter conditions resulted in a:

• 10.4% reduction in efficiency
• 8.5% reduction in driving range

Hybrid vehicles experienced a 12% decline in fuel economy.

The decline also translates into higher costs for motorists.

Vehicle Type	Estimated Added Cost per 1,000 Miles at 95°F
EV charged at home	$6.78
EV using commercial charging	$16.25
Hybrid vehicle	$13.02

On an individual trip, those amounts may be relatively small. Across thousands of miles and repeated periods of high temperatures, however, the added expenses can accumulate.

Extreme Temperatures Are Associated With More Severe Crashes

The most significant findings involve the potential relationship between heat and traffic crashes.

Research included in Attorney Brian White’s analysis examined more than 1.4 million crashes across 177 California cities.

At temperatures in the 99th percentile, researchers found the relative risk of a severe crash rose to 1.35, while the relative risk of a fatal crash reached 1.22.

The study also identified elevated risks involving pedestrians and cyclists and a stronger relationship between heat and crash risk at intersections.

These findings establish an association rather than proving that heat directly caused specific crashes.

Separate research examining U.S. traffic fatalities found that fatal crashes were approximately 3.4% more common on heat-wave days than on comparable non-heat-wave days.

Together, the findings suggest that exceptionally hot weather may affect driving conditions through multiple pathways, including driver behavior, vehicle performance and road conditions.

Roadside Breakdowns Can Create a Second Safety Hazard

When mechanical problems occur, the danger does not necessarily end once a vehicle stops moving.

AAA Foundation research found that more than 2,100 people were killed outside disabled vehicles between 2019 and 2023.

Those deaths were not identified as heat-related, but they demonstrate the risks that arise when motorists become stranded along active roadways.

A battery failure, tire problem or overheated engine can force drivers and passengers into environments where vehicles may be passing only feet away at highway speeds.

During extreme heat, stranded motorists may also face dangerous environmental exposure while waiting for assistance.

Arizona Pavement Became Hot Enough to Cause Severe Burns

Road surfaces themselves can become dangerous under extreme summer temperatures.

Between June and August 2023, 136 people were treated for severe pavement-contact burns at Arizona’s Valleywise Health burn center.

Among those patients:

• 14 died
• 34% required intensive care
• Many required skin grafts
• Some underwent multiple surgeries

The cases demonstrate how rapidly a transportation problem can become a medical emergency when road surfaces reach extreme temperatures.

People who fall, experience crashes, become stranded or are unable to move away from hot pavement can face severe burns within relatively short periods.

The Hottest States Have Nearly 14 Times as Many 90°F Days

The difference between states at opposite ends of Attorney Brian White’s ranking is particularly stark.

The 10 states with the highest heat-related driving risk averaged 63.8 statewide days at or above 90°F.

The bottom 10 averaged just 4.5 days.

That means the highest-risk states experienced, on average, more than 14 times as many 90°F days.

Traffic exposure also differed significantly.

The top 10 averaged 443,614 vehicle miles traveled per lane-mile, compared with 197,252 among the bottom 10.

The data suggest that motorists in the highest-risk states are not only experiencing much more persistent heat but are often doing so on more heavily utilized road systems.

Rising Temperatures Could Add Billions to Road Costs

The economic consequences extend beyond individual vehicle repairs.

One national pavement study included in the analysis projected that rising temperatures could add approximately $19 billion to U.S. pavement costs by 2040 under a moderate warming scenario.

Under a higher-warming scenario, additional costs could reach approximately $26.3 billion.

The federal PROTECT program has allocated $8.7 billion over five years toward improving transportation resilience against climate and weather-related hazards.

For motorists, crashes can create much larger financial consequences than ordinary maintenance.

National Safety Council estimates cited in the study put the economic cost of a property-damage-only crash at approximately $6,600 per damaged vehicle.

A disabling injury was estimated at roughly $174,000, while a motor-vehicle death carried an estimated economic cost of approximately $2.05 million.

Those estimates apply to crashes overall and are not calculations of heat-specific crash costs.

How Attorney Brian White Ranked Heat-Related Road Risk

The analysis ranked the contiguous 48 states using six indicators.

Measure	Weight
Average summer maximum temperature	20%
Statewide days at or above 90°F	20%
Statewide days at or above 100°F	15%
Longest continuous period at 90°F or hotter	15%
Vehicle miles traveled per lane-mile	15%
Share of pavement rated poor	15%

Climate measures were based on June through August 2025 NOAA data, while transportation measures used 2024 Federal Highway Administration data.

Alaska and Hawaii were excluded because comparable finalized NOAA statewide daily-grid information was unavailable for the climate measures used in the ranking.

The resulting score measures comparative exposure to heat-related road conditions, rather than predicting the probability that a particular driver will be involved in a crash or experience a breakdown.

Still, the findings reveal substantial differences between states.

Arizona stands out for the country’s most extreme combination of persistent summer heat, while Louisiana’s deteriorated pavement pushes its overall risk above hotter Texas. Florida and California combine heavy road use with significant heat exposure, creating another type of transportation challenge.

Taken together, Attorney Brian White’s analysis suggests extreme heat is becoming increasingly relevant to virtually every part of the driving environment.

The effects can begin with softer pavement or reduced vehicle efficiency and progress to tire failures, roadside breakdowns, emergency repairs and potentially more severe crashes.

For drivers in the country’s hottest states, summer heat is increasingly more than a weather issue. It is also a road-safety, infrastructure and transportation-cost issue.