PHOENIX—“An unusually hot and dry summer.”

That’s what residents of the nation’s hottest city can expect yet again this summer, following last year’s heat wave in which temperatures soared past 110 degrees Fahrenheit for 31 days straight—a record that ultimately resulted in a record 645 heat-related deaths, Mayor Kate Gallego said in front of the city’s new 24-hour heat respite center located downtown in front of the Burton Barr Library.

The mayor’s speech Monday kicked off Heat Awareness Week in Phoenix as leaders of the nation’s fifth-largest city work to raise awareness about the sweltering summer to come and the resources available to help residents deal with it. This year, Phoenix will have two overnight heat respite centers for the first time and will extend cooling center hours at three other locations across the city. 

“Phoenix residents know the summer heat well,” Gallego said. “But the season is becoming increasingly severe, especially for our neighbors who are unsheltered, those who work outdoors and those with health conditions. That means we must be more vigilant and spread awareness about how to keep yourself, your loved ones and all of our community members safe during extreme temperatures.”

Heat is nothing new in the Valley of the Sun. It’s dry, and hot temperatures are often the first thing to come up in conversations about living in the city. But those dry summer temperatures are getting worse. When last year’s stretch of 31 days above 110 degrees finally ended, the high was still 108 degrees. In total, the city saw a new record for the number of days reaching 110 degrees—54—barely beating out 2020’s 53 days that reached that temperature or higher. Experts expect this summer to be similar to last year. 

“What we’re looking at for trends for this upcoming summer is above normal temperatures and below normal precipitation when we get into monsoon season,” said Tom Frieders, the meteorologist coordinating weather warnings for the National Weather Service in Phoenix. “Those two kind of go hand in hand. When you don’t have the storms and the clouds to cool you down, it elevates the temperatures to that next level and that’s what we saw last year.”

Two factors are driving the increased temperatures: climate change and the sprawling development of the Valley. During the last year, the world saw 11 consecutive months of record global heat, and forecasts for the summer predict above-average temperatures across much of the Western U.S. and East Coast.

In Phoenix, those higher temperatures are heightened by how the city is built. Unlike some other U.S. metropolises, Phoenix and its suburbs largely developed post-World War II, when single-family homes, automobiles, freeway systems and air conditioning had taken hold of American life, leading to the valley’s “unrelenting sprawl.”

More roads encouraged driving and the burning of fossil fuels, and also absorbed solar radiation to contribute to the creation of heat islands. Sprawling developments of asphalt roads and homes retain heat overnight. At Phoenix’s Sky Harbor International Airport, nighttime temperatures in the summer have risen by almost 9 degrees Fahrenheit while daytime temperatures have risen by around two to three degrees over the past 60 years. As the region heats up, A/C systems that make indoor temperatures more livable require more energy—also usually generated by burning fossil fuels—and those systems also emit heat outside while keeping buildings cool. 

Together, climate change and sprawling heat islands have led the city’s summers to get hotter and deadlier. The number of heat-related deaths has been increasing in Maricopa County, home to Phoenix, since 2014. Last year’s 645 heat-related deaths were a 52 percent jump from 2022, with heat increasingly being the primary cause of those deaths and not just a contributing factor.

But the heat doesn’t impact the city equally. The shadiest and coolest parts of the city are found in the city’s wealthier neighborhoods. Of last year’s heat deaths, about 75 percent occurred outside and 45 percent were unhoused. 

David Hondula, the director of Phoenix’s Office of Heat Response and Mitigation, said a major lesson from last year was “that we can be much more coordinated” in responding. “When the forecast really started looking dire as we were in mid-June heading into July last year, we did pull people together. We did do more,” he said. “But that really needs to happen in October and December, January and March because everything takes time to line up.”

Staffing is the most important thing, he said, especially finding workers trained in conflict de-escalation and mental health care, as the city ramps up its services like cooling centers and expands how long they are available. “Without the right expertise, and without the sufficient bodies with that expertise, we couldn’t operate at all,” Hondula said. 

He said the city is better prepared this year, with leaders from across the county working together. The city is looking at extending operating hours at some of its cooling center locations by 40 to 50 percent, he said, and increasing its investment in the 2-1-1 Arizona Information and Referral Services program, where residents can dial 211 to get help with anything ranging from finding where the nearest cooling center is to getting help fixing a broken air conditioner. 

Though the cooling centers will help, more needs to be done to better keep Phoenix cool in the years to come, and that starts with doing more to address how the city is designed, Gallego and Hondula said. Planting more trees has been a big part of the city’s planning for addressing the heat, though the city is falling behind the goals it committed to achieve by 2030. The city has planted around 700 new trees this year, with more on the way thanks to funding from the American Rescue Plan Act of 2021, Hondula said, and it is working to better collaborate with private landowners to plant even more. He added his office was also involved in updating the city’s ordinances to better address heat, such as requiring contractors hired by the city to have a heat safety plan for outdoor workers, something he hopes they can continue chipping away at and expand throughout the city.

“When we compare the investment that we’re making, to how society values life as represented through the federal government’s value of a statistical life, one life saved, the whole thing is worth it many times over,” Hondula said.