Climate Change and the Rising Frequency of Heat Waves

Heat waves in the United States now occur roughly twice as often as they did in the 1980s, according to the federal government's Fifth National Climate Assessment. For anyone responsible for treating exertional heat stroke, whether on a fire department, at a sports event, or on a job site, that trend translates directly into more days of elevated risk per year.

Frequency, not just intensity

Public attention tends to focus on record-breaking single-day temperatures, but the more consequential shift for planning purposes is duration and frequency. Longer heat waves mean more consecutive days of physical exertion in dangerous conditions, which compounds risk for anyone whose job or sport involves repeated exposure rather than a single hot afternoon.

The mortality trend confirms the exposure trend

CDC data shows heat-related deaths in the US have more than doubled over the past decade, with a JAMA analysis finding the death rate accelerating sharply, at roughly 16.8% per year, between 2016 and 2023. This is not simply a function of an aging population: more than one in five heat-related deaths occur in people aged 15 to 44, the age range most represented in exertional heat stroke cases.

What this means for operational planning

A response built around historical seasonal averages is increasingly outdated. Fire departments, event medical directors, and EHS managers who plan cooling capacity based on last decade's typical summer are likely under-resourced for the frequency of extreme heat days their teams will actually face this season and in seasons to come.

Building capacity that scales with the trend

Because heat waves are becoming more frequent rather than occasional, cooling equipment needs to be a standing part of operational readiness, not an emergency purchase after a bad summer. The Kollder emergency cooling tub's compact storage and sub-2-minute deployment make it practical to keep on hand year-round. More at kollder.com/#contact.

Further Reading

• Monitoring Exertional Heat Stroke Risk: WBGT by Region
• Two Decades of Public Health Heat Response
• Canicule et réchauffement climatique : les vagues de chaleur en France (FR)
• Request a Kollder Quote

Sources: CDC WONDER, National Vital Statistics System, Fifth National Climate Assessment, JAMA (heat-related mortality in the United States, 1999-2023, 2024).