In Brief:
- Heat-related deaths went down in Phoenix in 2024, the first year-over-year decrease in a decade.
- A data-driven approach has helped the region identify who is most at risk and target its public health response more efficiently.
- The city is at the leading edge of a national effort to better understand how to keep cities safe during extreme heat events.
Last year, residents of Phoenix suffered through 113 consecutive days of temperatures over 100 degrees. It was the longest such streak ever recorded, a month longer than the 1993 record of 76 days.
Something else that was remarkable also happened in 2024: Heat-related deaths in the Phoenix area went down, the first year-over-year decrease since 2014.
“By any measure, last year was the hottest on record for the city of Phoenix and Maricopa County,” says David Hondula, the city’s director of heat response and mitigation and a researcher at Arizona State University. “If everything else had remained the same as the year before, we would have expected the numbers to go up.”
The biggest change in heat relief, he says, was the opening of the city’s first 24/7 heat respite and navigation center. The city also operates an overnight center and three cooling centers in public libraries.
Over the summer, 5,000 unique visitors came to these five facilities for 35,000 visits, Hondula says. They offer a gateway to other city services and on-site medical care.
In all, the city contributes about 60 facilities to a regional heat relief network of more than 200. Some are hosted by other municipalities, some by nonprofit or faith-based groups.
Coordination between the members of this network was the best it has ever been in 2024, says Ladd Keith, an urban heat researcher at the University of Arizona. “It’s almost impossible to know what caused the drop in deaths, but the coordination certainly assisted,” he says.
Relief is just one part of a multipronged response to extreme heat. Fatality data collected by the city and county show that those most likely to succumb have problems that don’t begin and end with heat.
Understanding Risk
Maricopa County — which includes Phoenix — has been monitoring heat-related deaths since 2006, according to Nick Staab, the county's chief medical officer. Drawing on data from sources including the county medical examiner, local hospitals and the National Weather Service, the county Public Health Department publishes an annual mortality report. It also updates a heat-related illness and death dashboard weekly, to give community members a real-time view of the interplay between heat and illness.
It's unusual for a public health department to have such rich data on heat and health, or the nuanced view of risk it brings. For example, the 2024 report reveals that over half of all heat-related deaths occurred on days of “moderate” heat risk.
“You can’t have a plan only on extremely hot days,” Staab says. “Those moderate days can really add up, and if you’re vulnerable, the cumulative effect can be very dangerous.”
Almost half of those who died of heat-related causes in 2024 were homeless, underscoring the role of housing programs in reducing these fatalities. Substance abuse was a factor in almost six in 10 deaths, primarily methamphetamine. In March, the county department of mental health directed more than $4 million in opioid settlement funds to strengthen substance use response. Opioid overdoses are more likely when they are used in combination with meth.
Seven in 10 indoor deaths occurred in structures without a functioning air conditioner, and the great majority were only discovered as the result of a welfare check. A weatherization assistance program and an air conditioning program can help low-income families keep their homes safe.
Pre-existing conditions increase risk, heart disease most significantly. “It's not just the exposure to heat, it’s the resilience of individuals and their ability to survive in the heat that is based on so many other factors,” Staab says. This means it’s vital for cooling centers to be able to connect visitors to county resources.
Heat relief visits have resulted in housing for more than 800 people in Phoenix last year, Hondula says. “Being placed in housing, having access to health and medical services, being reconnected with family members — those are all really important parts of the heat vulnerability and heat resilience story of our community.”
Not Just the Southwest
A June 2021 “heat dome” in the Pacific Northwest — a phenomenon in which atmosphere pressure traps hot air over a region — led to more than 100 deaths in just one week, and forced reconsideration of who needs to be concerned about heat mitigation. This June, 245 million Americans sweltered under a dome that formed in the Northeast.
“One of the worries that's always in the back of my head as a heat researcher, is that we don't want every community to have to experience a record-breaking heat wave that causes mass death before they take heat seriously,” Keith says.
Keith points to the HEAT.gov website, a resource from the federal government, as a starting place for mitigation insights, including tools for assessing heat and health risks and planning responses to heat events. (Some resources there have recently been taken down, he says.) Planning for Urban Heat Resilience, a book Keith coauthored with support from the National Oceanic and Atmospheric Administration, is available at no cost from American Planning Association.
Other jurisdictions are contacting Staab to learn how Maricopa County collects the data it uses to understand who is most at risk from heat stress. “Our success is largely based on our relationship with the medical examiner’s office [to collect data],” he says. “I’ve been encouraging local health departments to reach out to establish that relationship.”
As the national conversation about heat has evolved, so have networking opportunities for states experiencing extreme heat, Hondula says. He’s on the steering committee of an Arizona State-based heat resilience work group that monitors forecasts, shares ideas for relief and response and fosters collaboration between organizations responsible for mitigation.
“We need more mechanisms to talk to each other, to learn what’s happening," Hondula says. "Even in cities where there aren’t named heat officers, there are heat leaders doing amazing work.”
More to Do
The bottom line is that every heat death is preventable, Keith says. “I think a lot of folks that work on heat in Arizona were feeling dismayed that the numbers just kept rising. At the very least, 2024 shows that with coordinated response, we can curb the tide of heat deaths.”
Although it was encouraging to see the numbers go down for the first time in a decade, Hondula notes, there’s still more work to do. “When I came to Arizona 10 years ago, in a really bad year we might have upwards of 100 [deaths]. We’re well above that number today.”
But there’s optimism among community leaders that the right mix of investments can lead to significant declines. Recent years have been “transformative” in terms of engagement from multiple levels of government, Hondula says.
“I’ve been attending heat meetings for a long time in Arizona, and the conversation has transformed from ‘Do we think people will show up?’ to ‘Wow.’”
