“Even if you live in the suburbs, there is some relevance when you think maybe [from] your nice shaded house, you go to the shopping plaza by the highway and you feel how much hotter it is there,” said Jen Brady, senior data analyst at Climate Central. “It’s because you have this dense built environment.”
The new analysis is essentially a more detailed and tighter focused version of a report Brady helped lead in 2021, which created an index to measure the intensity of urban heat islands and then ranked the nation’s 159 most-affected cities. That index generated an intensity score based on several things including population density, building height, and whether a surface reflects sunlight or absorbs and retains heat. Climate Central’s latest examination looked at 44 of the country’s largest cities by population, zoomed in, and applied the same index to nearly 19,000 census tracts.
“I was surprised at how far out the urban heat island effect was,” Brady said. “I was thinking once you got out of the city core, [temperature] was just going to jump off a cliff, you know, [from] eight degrees more to two.”
In reality, she said, the effects extend fairly far out. “You’re maintaining four to five degrees further and further outside even the city core.”