Phoenix heat-related deaths have doubled compared with this point last year, and officials are working to understand the drivers and how to respond.
Local health authorities report a 76% year-over-year increase. So far, 275 heat-related deaths have been confirmed in Maricopa County, and more than 500 additional cases are being reviewed as potentially linked to heat. If many of those are confirmed, the total could exceed 700 deaths. The county medical examiner noted he does not expect this year to surpass the 2023 record of 645, but it could rank as the second or third deadliest year. After two years of declines, any rise is troubling because officials consider these fatalities preventable.
Phoenix heat-related deaths and an earlier, hotter season
One clear factor is timing. Dangerous heat arrived earlier than ever across much of the West, with a climate change-fueled spring heat wave. Phoenix logged its first 100-degree day in mid-March, roughly six weeks ahead of the usual schedule and before the city typically opens cooling centers or other relief measures.
Summer then ranked as Phoenix’s second hottest on record. Much of the extreme heat was felt overnight, when temperatures repeatedly stayed high. Maricopa County Medical Examiner Dr. Jeff Johnston said nights that fail to dip below 90 degrees on consecutive days are especially risky. Phoenix historically averaged about seven nights a year in the 90s, but this year there were 29 such nights.
Research from Climate Central ties the sharp warming of summer nights to climate change and urbanization, a pattern seen in nearly every major U.S. city. Officials said one recent round-the-clock heat wave produced one of the largest spikes in heat deaths observed by the medical examiner’s office.
Cooling centers help, but funding is uncertain
Phoenix has invested millions in expanding hours at cooling centers to address overnight heat, and city leaders believe the effort is saving lives. The challenge is sustainability. Many sites rely on federal pandemic-era funding set to expire at the end of this year, creating uncertainty about whether services can be maintained or scaled up.
With the heat season starting earlier and nights staying hotter, public health officials say continued investment in heat relief will be critical to prevent further loss of life.
