PHOENIX — Heat-related deaths in metro Phoenix have surged this year after two seasons of improvement, with Maricopa County confirming 275 fatalities so far — a 76% jump from the same point in 2025 — and more than 500 additional cases still under review.
County Medical Examiner Dr. Jeff Johnston has said he does not expect to surpass the record 645 heat deaths logged in 2023, but totals could finish near the top of recent years. Public-health leaders treat virtually all of those deaths as preventable, making any rebound after declines especially concerning.
Dangerous heat arrived earlier than usual. Phoenix logged its first 100-degree day in mid-March — about six weeks ahead of a typical year — before cooling centers and other relief programs usually ramp up. Summer then ranked among the hottest on record, driven less by daytime peaks than by nights that refused to cool.
Johnston pointed to consecutive overnight lows that stayed above 90 degrees as especially deadly. Those nights used to average roughly seven a year in Phoenix; this year the Valley logged 29. During one stretch of round-the-clock heat, the medical examiner’s office saw one of its sharpest spikes in heat deaths.
Phoenix has spent millions expanding cooling-center hours and says those sites are saving lives. Much of that capacity, however, still rides on pandemic-era federal aid scheduled to expire at the end of 2026 — leaving open whether overnight heat relief can scale as summers keep intensifying.