KJZZ is a service of Rio Salado College,
and Maricopa Community Colleges

Copyright © 2025 KJZZ/Rio Salado College/MCCCD
Play Live Radio
Next Up:
0:00
0:00
0:00 0:00
Available On Air Stations

Phoenix has broken the record for most nights with low temperatures in the 90s

A Phoenix skyline
Getty Images
The sun sets over Phoenix.

Before the doors open for overnight heat relief at the Senior Opportunities West center, south of downtown Phoenix, there’s already a crowd of people waiting to get inside.

Among those in line is Adaline Goytia. She’s 71 and recovering from a stroke. She said she was supposed to move cross-country recently, but the people who were going to help her couldn’t make it to Phoenix.

“I got stranded here,” said Goytia, who has spent every night since at the heat relief site.

Another regular is George Threadgill. He’s been homeless for about three years and used to spend summer nights on a park bench. This summer, he’s spent every night in the cooling center. He said he appreciates the peace and quiet at the facility, but said the air conditioning doesn’t hurt.

“It feels rather good in here,” Threadgill said.

Then there’s Blanca Corral. She’s here because she and her boyfriend lost their lease on their apartment weeks before they could get into the new place they lined up. To complicate matters, she’s pregnant.

“I’m tired, but God wanted to send the baby now,” Corral said in Spanish.

People seeking overnight heat relief line up outside Phoenix's Senior Opportunities West Center on July 25, 2024.
Katherine Davis-Young/KJZZ
People seeking overnight heat relief line up outside Phoenix's Senior Opportunities West Center on July 25, 2024.

There are no beds at this site — which still serves as a senior center during the day, then reopens from 6 p.m. to 5 a.m. for heat relief — but guests can nap in chairs. With homeless shelters across the metro area at capacity, demand for those seats this summer has been enormous. The city reports its five sites that offer overnight or extended evening hours for heat relief have had more than 20,000 visits since May. That number includes repeat visitors like Goytia, Threadgill and Corral. Nearly 90% of visitors to the sites have been homeless.

This is the first summer the city has offered overnight or evening hours at any of its cooling centers. That timing has proved critical — summer nights have never been hotter. Phoenix has now set a new record for the most nights with low temperatures in the 90s in a year. As of Tuesday, 36 nights this summer have stayed above 90 degrees. And the city could record even more 90-degree nights before the end of August.

“This has not been a fun summer for a lot of people, and unfortunately, the problem particularly is that we don’t get any relief at night,” said Randy Cerveny, a professor of geographical sciences at ASU and rapporteur on extreme records for the World Meteorological Organization.

That’s troubling, Cerveny said. “We’re having more record minimums than we are record maximums.”

While daytime highs have shifted gradually over the last couple of decades, Cerveny said overnight lows have shot up exponentially.

“Back before 2000, we would have basically five or less days in which the temperature didn’t go below 90,” Cerveny said.

The 36 lows of 90 degrees or hotter recorded so far this summer at Phoenix Sky Harbor International Airport break the record of 35 90-degree lows set just last year. The previous record of 28 nights with lows in the 90s had been set in 2020. Prior to that, Phoenix had never before had more than 15 nights in the 90s in a single year, according to the National Weather Service.

National Weather Service

Nights are warming nationwide, but the trend has been especially dramatic in Phoenix. According to climate research group Climate Central, from 1970 to 2022, summer nights across the U.S. got about 2.6 degrees warmer. Over the same time period, Phoenix’s summer nights got 5.8 degrees hotter.

The urban heat island effect is partly to blame. As Phoenix’s population has boomed, the metro area has been paved over with more and more heat-trapping concrete.

But Cerveny thinks Phoenix’s spike in the number of 90-degree nights over the last few years has more to do with greenhouse gas emissions.

“Carbon dioxide traps in the heat that’s collected during the day and therefore we get hotter during the night,” Cerveny said. “It’s one of the clear indications that we have that climate change is going on.”

Cerveny said he expects Phoenix is likely to record its first overnight low temperature of 100 degrees in coming years. The hottest night in Phoenix history was July 19, 2023, when the low temperature was 97 degrees. Cerveny expects that record will fall sooner than Phoenix’s all-time high temperature record of 122 degrees, set in 1990.

And round-the-clock heat comes with consequences. It stresses vegetation. It drives up demand for electricity. And it creates serious health risks, especially for unsheltered people, said Dr. Nick Staab, assistant medical director for Maricopa County Public Health.

“It just doesn't give the body enough time to recover from those really high temperatures that we're experiencing during the day,” Staab said. “So we also see increased heat-related illness related to those high overnight lows.”

Staab’s department analyzed five years’ worth of Maricopa County hospital records and found 90-degree nights resulted in 150% more heat-related illness cases than 80-degree nights. And people experiencing homelessness faced 100 times greater risk for heat-related illnesses than the general population, the report said.

The goal of opening the Senior Opportunities West center and a few other Phoenix heat relief sites at night this year was to reduce heat-related illness and deaths, which have soared over the past decade.

So far this summer, Maricopa County has confirmed 114 heat-related deaths and is investigating 465 possible heat deaths. Those numbers are about 10% lower compared to the same time last year. Still, 2024 appears likely to be one of Maricopa County’s deadliest summers on record.

And future summers could bring an even more daunting challenge. Nights are likely to be even hotter. Meanwhile, people are still becoming homeless in Maricopa County at about twice the rate homeless people are finding housing.

For now, Goytia is grateful at least to have had an option for getting inside this summer when she became homeless for the first time at 71.

When asked what might have happened to her had the city not made the Senior Opportunities West center available for overnight heat relief this summer, Goytia said, “I hate to think of it, to be honest.”

Like others at the cooling center, she’s just trying to get through the summer, one night at a time.

Katherine Davis-Young is a senior field correspondent reporting on a variety of issues, including public health and climate change.
Related Content