Bad news for health: The number of extreme heat days in Utah could double by 2050
This summer’s heat — however intense — might pale in comparison to the baking conditions Utahns will experience just one generation from now.
One federal climate projection expects the number of Utah days with extreme heat in 2050 to be more than double the state’s historical average from 1976-2005.
For many Utahns, that swell of hot days could have serious health consequences. Heat already causes more deaths in the U.S. than any other weather hazard. In 2021, 375 Americans died of heat-related events. That’s more than all the deaths caused by floods, tornadoes and the cold combined.
Morgan Zabow, the community heat and health information coordinator with the National Integrated Heat Health Information System, said hot weather’s impact on human health needs to be getting more attention, especially since most heat-related illnesses and deaths are preventable.
“Every city needs to be taking heat seriously,” Zabow said. “Unfortunately, since we're heading toward a hotter world, it's something we really need to be thinking about right now.”
A county-by-county map created by the NIHHIS shows how this hot weather scenario could play out in Utah. The map is based on climate projection data from the National Oceanic and Atmospheric Administration that shows how temperatures will keep warming nationwide if greenhouse gas emissions continue as they have been.
Salt Lake County would see its number of extremely hot days double from a historical average of 30 days per year to 60 days per year. Utah County would experience a similar bump from an average of 21 days per year to 51 days per year.
That means the most populated part of the state would get an extra month of extreme heat — which this dataset defines as temperatures at or above 90 degrees — each year.
Because of the urban heat island effect, neighborhoods with more concrete than trees can have localized temperatures 15-20 degrees higher than surrounding areas. And unfortunately, Zabow said, those neighborhoods also tend to be places where many high-risk people — such as the elderly and those with heart disease or diabetes — live and work.
“A lot of times, the most disproportionately impacted populations are living in the hottest neighborhoods,” Zabow said.
The NIHHIS plans to conduct a heat mapping project in Salt Lake City to pinpoint the hottest parts of town where cooling resources should be directed, which Zabow said should be released by this fall.
The hardest hit parts of the state, in terms of percentage increase, are also the ones that aren’t as used to dealing with this kind of heat. The number of extreme heat days in mountainous, high-elevation counties such as Piute, Carbon and Morgan would more than quadruple.
Some areas that historically only used to deal with one day of 90-degree temps in a summer — like Summit and Rich counties — would end up getting more than a dozen such days each year.
In places that aren’t used to much extreme heat, homes are less likely to have air conditioning. That increases the risk of heat illness because people’s bodies don’t have a chance to recover, Zabow said, as evidenced by the 2021 heat dome that killed hundreds of people in the typically cool Pacific Northwest.
As climate change makes extreme heat more likely in these high-elevation parts of Utah, Zabow said, it increases the need for community cooling resources, such as extending the hours of air-conditioned public spaces like libraries or malls.
In southern Utah, the hottest part of the state would just keep getting hotter. Washington County is expected to get 97 days of extreme heat by 2050, up from an average of 60 days. Grand and San Juan counties would see their average of 52 days per year rise to 87 days and 90 days, respectively.
That extends the season of extreme heat across southern Utah’s red rock country until it covers basically one-fourth of the year.
That could create a dangerous situation at the region’s outdoor recreation sites, such as Zion National Park, which welcomed more than 4.5 million visitors from all over the world last year — most of them coming during the hottest months.
Jonathan Shafer, a spokesperson for Zion National Park, said many of those travelers who come from cooler places aren’t physically and mentally prepared for southwest Utah conditions.
“It's common to get here and think that you're going to be able to recreate here the same way that you could in an area where you've come from,” Shafer said. “The reality is that this can be an extreme place.”
The park typically oversees around 100 search and rescue operations each year. Last year, Shafer said, there were 120, and a substantial portion of those had to do with heat. On summer days, he said, it’s not uncommon for the park’s paramedics to respond to heat-related emergencies.
Heat affects people differently depending on how much their body is acclimated to it. It’s like how people who live at high altitude don’t need to adjust to the lack of oxygen in the air the same way that people who just stepped off a plane from the coast do. So someone who’s lived in southern Utah all their life is likely better able to handle the heat than someone who’s coming to the region from somewhere cooler.
That’s why park staff have ramped up their efforts to increase awareness about heat illness and how to avoid it while still enjoying the park.
Zion often posts heat health tips for its multitude of social media followers, has signage about heat illness prevention and even places rangers at trailheads to give hikers one last verbal check about their preparedness for the hot conditions.
There are also free water bottle filling stations throughout the park, and rangers remind people to use them.
“We refer to sharing that information as preventative search and rescue,” Shafer said.
To protect park staff, Shafer said, Zion sometimes postpones outdoor maintenance work that was scheduled for a hot day or moves interpretive programs indoors.
He can’t think of a time when the park closed down a trail specifically as a precaution against heat illness, but there’s precedent set by the many times parts of the park have been temporarily closed for flooding concerns.
And as heat waves become more frequent and intense, Zabow said, closing down hiking trails in the name of public safety might become more common.
There are lots of things individuals can do to lower their risk — drinking extra fluids, wearing light clothing, staying out of the sun during the heat of the day — she said, but at some point, extreme heat takes its toll.
That’s why places like Utah need to plan for a hotter future.
“Not just how we can work on heat right now,” Zabow said, “but also thinking in the long-term scale of how we can take actions now to make sure that our community is protected 10, 20 or 30 years from now.”