Under the Sun and Under Strain: New Research Shows How Summer Heat Endangers America’s Truck Drivers
Heat as a Driver Safety Hazard
Extreme heat is one of the most lethal weather‑related threats in the United States. With more than a thousand heat‑related deaths annually, the danger extends far beyond discomfort. For truckers, heat affects both the body and the vehicle. Engines overheat, brakes lose efficiency, and batteries fail more frequently. These mechanical issues increase the likelihood of breakdowns and crashes, especially during long summer routes.
Climate Trends Intensify the Problem
The study notes that U.S. temperatures continue to rise, with some regions expected to see summer increases of up to six degrees. Even small temperature shifts can have major consequences for road safety. Hot pavement softens, tires degrade faster, and cooling systems operate under greater strain. These factors combine to create hazardous conditions for drivers navigating long stretches of highway.
Injury Risk Rises with Temperature
A major occupational injury analysis found that injury risk increases significantly once temperatures exceed 85 degrees. For truckers, who often work in confined spaces with limited airflow, the danger is even greater. The study estimates that more than one percent of all occupational injuries in 2023 were linked to days above 70 degrees. Heat affects concentration, reaction time, and physical stamina, all of which are critical for safe driving.
Cognitive and Physical Strain
Heat exposure affects mental performance, with consecutive days above 95 degrees impairing cognitive function. This can slow reaction times and reduce alertness, increasing crash risk. The study also highlights the long‑term effects of UV exposure. A medical case involving a veteran truck driver showed severe sun damage on the left side of his face, illustrating how years of driving with sunlight streaming through the window can cause lasting harm.
UV Exposure Rankings
The research ranks states by UV irradiance, revealing where truckers face the highest exposure. Southwestern states dominate the list, with Arizona, New Mexico, and Hawaii leading. California ranks fifth, underscoring the intense sunlight drivers face in the region.
Highest UV Exposure
| Rank | State | UV Irradiance |
|---|---|---|
| 1 | Arizona | 4,931 |
| 2 | New Mexico | 4,797 |
| 3 | Hawaii | 4,793 |
| 4 | Florida | 4,596 |
| 5 | California | 4,541 |
| Rank | State | UV Irradiance |
|---|---|---|
| 1 | Alaska | 1,957 |
| 2 | Vermont | 2,873 |
| 3 | New Hampshire | 2,921 |
| 4 | Maine | 2,937 |
| 5 | Massachusetts | 3,002 |
Several high‑profile cases illustrate the consequences of extreme heat. In Texas, a UPS driver collapsed and later died after suffering heat‑related symptoms. OSHA fined the company for failing to provide adequate medical access. Another case in New Mexico resulted in a $220 million verdict after a tire failure linked to heat caused a fatal crash. A separate lawsuit alleges that heat‑accelerated brake failures in certain trucks contributed to dangerous malfunctions.
UPS Drivers Speak Out
A 2025 case study highlights the struggles of UPS drivers working in trucks without air conditioning. Workers reported cargo areas reaching temperatures as high as 152 degrees. Despite commitments to upgrade fleets, only a fraction of promised air‑conditioned vehicles were in service. Between 2015 and 2022, more than 140 UPS employees were hospitalized for heat‑related injuries.
Summer Crash Trends
Crash data shows that summer months consistently produce high numbers of truck crashes and fatalities. Between 2022 and 2026, June, July, and August each recorded more than 19,000 crashes. Fatalities also peaked during these months, with August topping the list.
Summer Crash Totals
| Month | Crashes | Fatalities |
|---|---|---|
| June | 19,475 | 1,695 |
| July | 19,446 | 1,653 |
| August | 20,403 | 1,789 |
Contrary to common assumptions, most weather‑related truck crashes occur during clear, warm conditions—not icy or snowy weather. Dry roads, hot pavement, and high temperatures create conditions that increase crash likelihood.
Regional Crash Hotspots
Southern and Midwestern states recorded the highest crash rates per capita in 2025. These regions combine heavy freight traffic with long rural highways and intense heat.
Highest Crash Rates
| Rank | State | Crashes |
|---|---|---|
| 1 | Arkansas | 78.56 |
| 2 | South Carolina | 78.29 |
| 3 | Missouri | 76.64 |
| 4 | Georgia | 75 |
| 5 | Indiana | 71.65 |
Lowest Crash Rates
| Rank | State | Crashes |
|---|---|---|
| 1 | Alaska | 2.03 |
| 2 | Hawaii | 6.5 |
| 3 | Rhode Island | 9.89 |
| 4 | New York | 16.43 |
| 5 | Massachusetts | 19.37 |
Fatal truck crash rates show a similar regional pattern. States like South Dakota, Oklahoma, and Nebraska top the list, while Rhode Island and the District of Columbia recorded zero truck fatalities.
A Call for Action
The study concludes that summer trucking is becoming increasingly dangerous as temperatures rise. Heat affects vehicle performance, driver health, and roadway conditions. UV exposure increases long‑term health risks, including skin cancer. Sweet James emphasizes that addressing these issues will require coordinated action from policymakers and transportation companies, including improved maintenance standards, better heat‑safety protections, and expanded access to air‑conditioned vehicles.
