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When the mercury soars in Salt Lake City, it’s more likely to affect people who are already vulnerable, a mix of federal data shows.
Citizen scientists gathered temperature data across the city in the morning, afternoon and evening on July 15, 2023. On that balmy Saturday, the average afternoon temperature was 92.4, and ranged from 87.2 to 98.
The hottest areas along the route those citizens scientists took around Utah’s capital city are more likely to be diverse or have residents with lower incomes and education levels — and sometimes both — according to a Salt Lake Tribune analysis of the results of the heat mapping campaign and U.S. Census Bureau data.
Rob Wilson, a local science teacher who helped organize the heat mapping campaign, said the data serves as a baseline to show where heat is distributed unevenly.
The data didn’t contain any surprises, said Debbie Lyons, the city’s director of sustainability, but rather “reiterated that our west side is generally hotter.”
The same coalition that applied to the heat mapping program has applied for a grant to build heat-resilient infrastructure, Wilson said.
That includes planting trees — something the city has committed to doing more — as well as landscaping and installing shades and structures for bus stops and other common areas, he said.
Salt Lake City will continue working to add trees and green space, Lyons said, and also has worked to update landscaping ordinances and make sure bus stations are shaded and comfortable.
“We’re not doing this just for climate change or just for air quality,” she said of the mapping campaign’s importance. “There is a real need to think about all the impacts development has on our community.”
Sun hits the west side first, creates ‘convection cycle’
There’s science behind why some areas of Salt Lake City are hotter than others, said Wilson, who teaches science at Rowland Hall, a private school in Salt Lake City.
As the sun rises over the Wasatch Mountains, he said, it hits the west side of the city first and “creates a sort of convection cycle.”
The thermals through the day are strongest on the west side, he said, and air from the east side pours west as the East Bench, Cottonwood Heights and other eastern neighborhoods get cooler air from the Cottonwood Canyons.
That contributes to a host of air quality problems on the city’s west side, he said, as well as temperatures generally being higher in historically redlined areas west of State Street.
Redlining was a common practice in the 1950s that discouraged banks from offering loans to minority families looking to purchase homes in white-dominated neighborhoods.
West of State Street is generally hotter than neighborhoods to east and north
The data from Wilson and others who mounted sensors on their cars and repeatedly drove routes around the city show those areas west of State Street generally are hotter — and that the easternmost parts of the city are much cooler on average in the afternoon.
As grouped by neighborhood, temperatures ranged from 89.5 to 93.4 and show a pattern of inequity with some exceptions.
(National Integrated Heat Health Information System) As grouped by census tract, temperatures measured across Salt Lake City during the heat mapping campaign in July 2023 ranged from 89.5 to 93.4 and show a pattern of inequity with some exceptions.
On average, residents in 25 neighborhoods (or “census tracts,” to use the government’s term for relatively permanent statistical areas) with average temperatures above 92.4 were 23.3% Hispanic or Latino and 1.6% Native Hawaiian or Pacific Islander, compared to 11.8% and 1.2%, respectively, in 28 areas with lower temperatures.
Household median income in hotter areas was, on average, about 40% lower than residents in areas where afternoon temperatures averaged below 92.4.
And residents in hotter areas were, on average, about 113.5% more likely to have not graduated from high school or passed an equivalency test.
There are some exceptions, such as a neighborhood near Rose Park where average afternoon temps were 0.7 degree below average, but where residents were much more diverse — including more than 50% identifying as Hispanic or Latino and 12.3% identifying as Native Hawaiian or Pacific Islander — and had lower incomes than the typical Salt Lake City resident. That neighborhood also is close to the Jordan River.
The data from the heat mapping campaign is different from a recent study showing how the built environment makes heat more intense across Salt Lake City. That study found even some wealthy areas get hotter because of hotspots with higher temperatures compared to surrounding areas.
But Climate Central focused on how heat islands boost temperatures, while the heat mapping campaign measured the actual temperature of those areas.
Wilson has presented the data from the mapping campaign several times and said he frequently points out that underlying health conditions are also more frequent in the west-side neighborhoods that are often disadvantaged because of their racial and ethnic or socioeconomic makeup.
That includes heat-related illness, he said, that’s compounded by other risk factors — including race and income, often correlating with not seeking health care.
Trees, shading infrastructure, evaluating Cool Zone network are potential solutions
There are solutions, Wilson said, and the group that secured funding for the heat mapping campaign has submitted another application to the U.S. Environmental Protection Agency for money to help with heat mitigation.
That does include tree planting, he said, but goes beyond the city’s commitment to increase the existing urban forest.
It also includes landscaping and shades and structures for bus stops and other areas people gather outside, Wilson said, and he’s advocated for it to include sunscreens to shade playgrounds.
Lyons agreed trees are a big part of mitigating heat islands, but not the only solution. For one, the city needs to make sure trees don’t just get planted but also get enough water, the major point of the ”Keep Your Cool” campaign.
Lyons said Salt Lake City is also working to:
Increase energy efficiency and update heating and cooling systems in single-family homes and multi-family buildings, such as apartment complexes.
Make sure people have cool places to go and provide misting tents and resource fairs for people experiencing homelessness.
Update current green spaces and rules for landscaping, like requiring tree irrigation systems in new developments and county tree canopy toward required plant cover.
Wilson added the grant the coalition has applied for would help evaluate the city’s existing cooling center network — a joint effort by the city and county that they call Cool Zones and that the coalition is calling resiliency centers.
The Cool Zone network includes all 18 branches of the Salt Lake County Library, said Sara Neal, spokesperson for the county’s library network.
“We care a lot about the health of our community,” Neal said. “For some people, that is having a place where they can be safe and get out of the heat.” That’s especially true for seniors, Neal said.
The group hasn’t yet heard back from the EPA about its grant application, Wilson said.
While local government and organizers work on solutions, he encouraged people to start thinking individually about “who’s vulnerable and what we can do to make them less vulnerable.”
Where to stay cool and learn more about programs
If you’re trying to avoid the heat, there’s a list of Cool Zones on the county’s website, slco.org.
To learn more about Salt Lake City’s tree planting and ways to help — including information on watering trees — visit the Urban Forestry page at slc.gov.
To learn more about what the city is doing about climate change and resiliency, go to slc.gov/sustainability/.
For information on the urban heat islands, heat forecasts and other resources you can visit Heat.gov.
Megan Banta is The Salt Lake Tribune’s data enterprise reporter, a philanthropically supported position. The Tribune retains control over all editorial decisions.
