Maricopa County has confirmed more than double the number of heat-related deaths so far this year compared to the same point last summer.
As of Tuesday, the Maricopa County Office of the Medical Examiner had confirmed 81 heat-related deaths in 2026. At the same point last year, 35 deaths had been confirmed. 587 more deaths from this year remain under investigation as potentially heat-related. That compares to 376 that were still under investigation at this point last year.
For the last two years, Maricopa County reported year-over-year decreases in heat-related deaths. Officials attributed the drops to local investments to expand access to cooling centers and other heat relief resources.
It’s too early to understand why the trend now appears to be reversing, said Kelli Donley Williams, deputy director of the Maricopa County Department of Public Health.
But, Donley Williams said, “the summer seemed to start so much earlier this year.”
Phoenix hit triple digits in mid-March, the earliest in the year the city has ever recorded temperatures above 100 degrees. The record-shattering early spring heat wave led to at least nine deaths, the highest heat-related death toll on record for the month of March in Maricopa County.
Donley Williams said bodies are not acclimatized to summer-like heat so early in the year. And, she said, agencies and organizations that run cooling centers and water distribution sites as part of Maricopa County’s Heat Relief Network typically only operate May through September.
“When you have a 100-degree day in March, it’s difficult to know what to do because we haven’t mobilized yet,” Donley Williams said. “So when we see those temperatures that early in the year, it’s dangerous.”
Donley Williams also noted overnight low temperatures have been especially hot this summer. Phoenix has had 21 nights with low temperatures in the 90s so far this year — triple the annual average. Public health experts say hotter nights often correlate with increased heat-related illnesses and deaths.
Longer heat seasons and hotter nighttime temperatures are both becoming more likely due to human-caused climate change, scientists say.
More scorching temperatures are in the forecast for Phoenix. The National Weather Service has issued an extreme heat warning for Maricopa County through Friday.
Donley Williams said Arizonans should take the health threats of heat seriously.
“None of us is smarter or stronger than this heat, we are all at risk,” Donley Williams said.
People lacking access to air conditioning in Maricopa County can arrange free transportation to cooling centers or get connected with other heat relief services by calling 211.
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