Report Shows Excessive Heat Pushes Worker Injury Risk Sky High

July 11, 2025

It may come as no surprise that heat-related worker injury claims rise on hot days, but the magnitude of the increase is an eye-opener.

As temperatures skyrocketed during early summer heat waves across the United States, the Workers Compensation Research Institute put out a webinar digging into the WCRI’S recent report on heat-related illnesses in the workplace. A recording of the webinar and presentation slide deck can be found on the WCRI website.

According to the report, heat-related illness (HRI) claims increase at least sevenfold on days when temperatures exceed 90 degrees, compared with days with temperatures between 75 degrees and 80 degrees. And the number of claims increases by as much as 18 times when it gets above 100 degrees.

“These are big increases in HRI counts on days when temperatures exceed these thresholds,” said Vennela Thumula, a senior policy analyst at WCRI and one of the study’s coauthors. “Even at 80-85 degrees Fahrenheit, we see that HRIs double.”

WCRI estimates that overall work injuries increase by 3% on days when temperatures are 90-95 degrees. Overall injuries are estimated to increase by 4% when temperatures exceed 95.

Excessive heat is reported to be the leading cause of weather-related deaths in the United States. The Bureau of Labor Statistics estimates show that 33,890 heat-related work injuries and 479 deaths occurred from 2011 to 2020.

Thumula believes the number of these injuries is likely an underestimate. Heat stroke, heat exhaustion, syncope, cramps, rash, rhabdomyolysis and acute kidney injury are all considered physiological heat-related illnesses.

Injuries that occur when heat impairs the perceptual, motor or cognitive abilities of workers and leads to accidents, such as falling off a ladder on a hot day, however, are more likely to be classified as falls or cuts as opposed to heat exhaustion.

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