Tree Shade Offers Heat Relief for Unsheltered People in Salt Lake City, University of Utah Study Finds

The University of Utah has released findings on how extreme heat affects people experiencing unsheltered homelessness in Salt Lake City. According to the study, these residents face hours of dangerous daytime heat and hot nights that offer little relief. Researchers also found that tree shade helps people feel measurably cooler, which makes it a critical resource for those without access to shelter.

The findings appear in *Unsheltered Homelessness and Extreme Urban Heat in Salt Lake County, Utah*, a report released Oct. 5 that brings together three U-led studies. The research combines real-time heat measurements with interviews with people experiencing homelessness and with local business staff. The goal is to identify heat risks, barriers to finding refuge and ways to provide better protection.

Jeff Rose, associate professor in the Department of Parks, Recreation, & Tourism at the University of Utah, is the lead author of the study and a coauthor of the report. He described the difference between people with and without housing: “When it’s hot, we go inside. If it’s cold, we go inside. If the air quality is poor, we have places to find refuge. If you don’t have access to secure housing, that’s a huge problem.”

The heat-measurement study was published Sept. 1, 2026, in the *Journal of Urban Health*. Researchers said it is one of the first to track personal, real-time heat exposure of people experiencing unsheltered homelessness. They followed eight participants in Salt Lake City from July 29 through Aug. 3, 2024. Participants carried GPS-enabled cellphones and portable heat sensors during their daily lives, which allowed researchers to measure their heat exposure and compare it with the surrounding tree canopy. Researchers collected nearly 10,000 heat-index observations covering the intensity and length of exposure during the day and overnight.

During daytime hours, participants spent nearly 20% of their time at moderate risk (91 °F). High (103 °F) and very high or extreme risk conditions (115 °F) were less common, occurring less than 4% of the time, but they did occur. Nights offered little relief. Participants spent an average of 69% of nighttime hours above the “hot night” threshold (68 °F), when sleep tends to be disrupted, and 16% in “very hot night” conditions (77 °F).

“Salt Lake City is getting hotter,” Rose said. “One of the things that really came out from our study is that people experiencing homelessness have a lot of hot nights where they’re not finding that low temperature at night that allows their bodies to re-regulate.”

Extreme heat can lead to heat exhaustion, heat stroke and other potentially life-threatening conditions. For people experiencing unsheltered homelessness, heat may worsen existing medical conditions, disabilities and mental health challenges. “This isn’t just about fairness and justice,” Rose said. “It’s also about survivability, particularly when we’re dealing with extreme environmental conditions.” His point is a call to defend those least protected from danger (Psalm 82:3).

The researchers found that time under tree canopy was associated with heat-index reductions of about 1.7 to 3.2 degrees Fahrenheit between noon and 6 p.m. The cooling effect increased with time beneath the canopy before tapering off after 15 minutes. Businesses and other indoor spaces may offer temporary refuge, but access is not guaranteed, so public trees can provide an alternative place to escape direct sunlight for people without shelter. Participants sometimes spent less than 10 to 15 minutes under the canopy because of access issues, which limited the shade’s cooling benefits. The authors emphasize that trees cannot replace secure housing or indoor cooling during extreme heat.

The October report also draws on preliminary findings from two additional U-led studies. Interviews with 24 people experiencing unsheltered homelessness found that access to shade, drinking water, bathrooms and places to rest can matter as much as the temperature itself. Participants described heat-related illness, disrupted sleep, emotional strain and displacement from public spaces, and many relied on community and mutual-aid networks for support. A third study, based on interviews with 30 business managers and staff, found that businesses often serve as informal cooling refuges, though access and practices vary. The report states that these spaces cannot reliably substitute for coordinated public cooling resources.

The report calls for a statewide “Code Red” policy that would activate emergency protections during dangerous heat. Proposed measures include extended access to public cooling spaces such as libraries and senior centers, and outreach to those at greatest risk. The researchers also recommend prioritizing tree planting and other cooling resources in hotter, heavily paved and underserved neighborhoods, including parks, riparian corridors, public plazas and other shared spaces.

Source: Read the original report