Why Phoenix sees little relief from hot temperatures overnight

There's little relief from the heat even when the sun goes down because of Phoenix's urban heat island effect.
Published: Jul. 11, 2022 at 8:45 PM MST
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PHOENIX (3TV/CBS 5) — Monday was the hottest day so far in 2022, reaching 115 degrees at Phoenix Sky Harbor. Unfortunately, there isn’t much relief overnight. The nighttime temperatures have been very warm, and there’s a reason for that. This is because of the urban heat island effect. Phoenix is growing and more people mean more buildings are going up, and roads are being paved. They absorb the heat, then slowly release it at night.

On the hottest day of the year, people are doing their best to stay cool, but even when we enter the overnight hours, it can still be challenging. “It feels like a sauna,” Jessica Whigam, visiting from Nashville, said. “We’re trying to stay inside more and drink a lot of water and a lot of fluids.” “It is so hot outside,” Valley native Tomeka Rychener said. “We got a mister and I just spray it on and it keeps you cool all day, hopefully,” one visitor from Prescott said.

“Once the sun goes down the buildings and the roads start releasing that energy but they do it much more slowly through the night so it keeps temperature really high,” Paul Iniguez, a meteorologist with the National Weather Service, said. Iniguez says communities are working on trying to mitigate this effect. “That’s usually changing the type of building structures you have and what the buildings are made out of, different reflectivity so if you use lighter colored materials that can reflect the sunlight back in the space so you’re not hanging onto it, or green cover canopy.”

This heat is no joke. Thirteen people in Maricopa County have died because of the heat already this year, and 92 deaths are under investigation. Heat-associated deaths have significantly increased over the years. Last year, there were 338 heat-associated deaths, which is up 69% from 2019. “Even if you’re someone who has lived here 10 or 20 years those temperatures have really gone up a lot the time you’ve been here,” Iniguez says.

For Tomeka Rychener, a born and raised Phoenician, it’s something she has noticed firsthand. “From a kid you could play outside all summer, you would go to the pool and you’ll get out and you could still sit on a bench or sit on a chair and you can’t do that now.” Iniguez says low temperatures are warming even faster than the highs temps, almost a full degree every 10 years.