As temperatures reached 97 degrees Fahrenheit in Colorado Springs on August 8, breaking a 57-year-old daily record, attendees at a music festival held at Blocktickets Park felt the heat.

More than 70 people in attendance at the Tacos and Tequila Festival were treated for heat-related illnesses, including at least seven who were hospitalized after “experiencing serious symptoms of dehydration and/or intoxication,” according to the Colorado Springs Fire Department, which declared the festival a “mass casualty” event.

The festival-goers were among a record number of Coloradans who sought medical treatment for heat-related illnesses this summer, amid unprecedented extreme heat fueled by climate change — a trend that’s projected to continue to intensify for years to come, as governments around the world struggle to curb the greenhouse gas emissions pushing global temperatures higher and higher.

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Between May 3 and August 8, a total of 1,124 patients in 18 of Colorado’s most populous counties were hospitalized or visited an emergency department or urgent care because of heat stroke, heat exhaustion or another heat-related illness, according to data from the Colorado Department of Public Health and Environment’s Syndromic Surveillance Program. Data for the state’s other 46 counties is not collected as part of the program.

Those figures put Colorado on track for a heat-related illness rate of 13.6 per 10,000 medical visits in summer 2026 — surpassing the previous record of 8.9, set in 2024, and more than double the rate observed when CDPHE began tracking HRI data in 2019.

Last month was Colorado’s second-hottest July in 132 years of record-keeping, and a heat wave lasting from July 25 to 28 was the state’s hottest four-day period on record, according to a report from the Colorado Climate Center last week.

More frequent, more intense heat waves are the most direct and unambiguous result of human-caused climate change to be felt in Colorado, state climatologists found in a 2024 report. Rising levels of greenhouse gases in the Earth’s atmosphere, mostly the result of burning oil, gas and coal, caused average global temperatures to rise by more than 2.3 degrees Fahrenheit over pre-industrial levels as of 2024, according to federal data — and parts of Colorado, including much of the Western Slope, are among the areas in the U.S. where average temperature increases have been most severe.

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What may sound like small upticks in monthly or yearly average temperatures can in fact mean big swings in the likelihood of extreme heat events. In the half-century before 1930, Denver recorded a high of 100 degrees or more less than once every seven years on average, according to the National Weather Service; since 2020, those days have occurred on average four times a year.

Globally, extreme heat kills more people each year than floods, hurricanes, wildfires and other weather-related disasters combined. But despite being one of the most straightforward impacts of a warming climate, this increasingly dangerous heat can be “invisible” to the public and to policymakers, said Sara Meerow, an associate professor of geography at the University of Colorado Boulder who studies planning and governance in an era of extreme heat.

“You don’t get the same dramatic photos that you do, say, from a wildfire or a hurricane, of devastation and destruction,” Meerow said in an interview. “People who are suffering from heat are often suffering alone. It doesn’t lend itself to the same sort of visible imagery, and also doesn’t always have really visible infrastructure damage.”

Communities that haven't historically thought a lot about about heat now really have to ... When it starts to become a chronic issue for a community, then you really have to figure out how to live with this.

– Sara Meerow, associate professor of geography at the University of Colorado Boulder

That may be especially true in Colorado, where the impacts of drought and wildfire often take center stage — and where residents are less accustomed to dealing with extreme heat, even as they quickly become more frequent. One 2017 city of Denver study estimated that if global greenhouse gas emissions continued to rise, the average number of 100-degree days could reach 34 per year by 2080.

“Communities that haven’t historically thought a lot about about heat now really have to,” said Meerow. “If it’s just a couple of days, people can change their routines. They can maybe escape to the mountains, go to the pool — you can adapt quite easily to that. When it starts to become a chronic issue for a community, then you really have to figure out how to live with this.”

Worker safety

Colorado’s hazardously hot summer comes as state lawmakers have struggled to pass a law requiring employers to take concrete steps to mitigate risks from extreme temperatures in the workplace. A bill introduced in 2025 would have required employers to provide shade or shelter in extreme conditions, implement temperature-related safety plans for job sites and make water available for workers. Amid opposition from business groups, it failed to advance out of committee.

A scaled-back version of the bill, introduced earlier this year, aimed to provide employers more “flexibility” in developing their own plans to be submitted to the Colorado Department of Labor and Employment for approval. But lawmakers eventually stripped out that provision, too, passing an even narrower version requiring CDLE to collect data on temperature-related injuries and publish a “model” injury prevention plan on its website.

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Injury risks for workers begin to rise at a daily heat index of 85 degrees Fahrenheit, and increase sharply above 90 degrees, according to a 2025 study that analyzed Occupational Safety and Health Administration data.

At the federal level, OSHA under President Donald Trump is moving to rescind Biden-era rules requiring employers to take steps like mandatory breaks and providing access to water and shade, The New York Times reported earlier this month.

Milton Jones, president of the United Food and Commercial Workers International Union, last week accused the Trump administration of “bowing to special interests and leaving workers at risk.” The UFCW represents tens of thousands of Colorado workers employed at meatpacking plants and grocery stores.

“Whether a UFCW member works in harvesting at a meatpacking plant in the summertime or fulfilling grocery orders outside in the sun, heat poses a potentially fatal risk to every worker,” Jones said in a statement. “Despite the progress made to establish a federal standard, the Trump administration has made it clear that it intends to side with big businesses fighting these protections rather than workers in danger of heat-related illness and death.”

Older people and people experiencing homelessness are also among those at significantly higher risk of injury, illness or death from extreme heat. Denver joined a growing number of U.S. cities when it began operating free cooling centers in 2021; all city recreation centers now open their doors as daytime cooling centers when the NWS issues a heat advisory for the region, though some advocates say the hours are too limited.

Cities like Denver — through its Office of Climate Action, Sustainability and Resiliency — are taking more proactive approaches to mitigating and managing extreme heat in the future, including through the hiring of “chief heat officers” and the development of heat action plans.

“I think all communities are going to have to do that — not just the larger, better-resourced cities in the state,” Meerow said. “The climate and the heat that we have experienced in the past is just no longer a good precedent. It’s no longer what we can expect in the future.”