Heat in one Arizona county played a role in 645 deaths last year

Arizona’s largest county shattered its record for heat-related deaths in 2023, a grim reminder of how dangerous last summer’s heat waves were for people vulnerable to rising temperatures. 

At least 645 people in Maricopa County — home of Phoenix and many of its suburbs — died from heat-related causes last year, according to a preliminary report from its Public Health Department released Wednesday. The deaths represented a 52% increase over the previous year. 

Deaths spiked during a record-breaking heat wave last July, the report shows. Temperatures reached 110 degrees Fahrenheit or above every day of July except the last day, according to National Weather Service data. Such remarkable temperatures would have been “virtually impossible” but for the effects of climate change, scientists reported last year. 

The new report shows clearly how heat waves and climate change intersect with social issues such as homelessness and substance abuse to put large numbers of people at grave risk. 

“This tragic number shows us how much work we still have to do,” Dr. Rebecca Sunenshine, the medical director for the Maricopa County Department of Public Health, said in a news release. “With a coordinated county-wide strategy, nearly every one of these deaths can be prevented.”

About 65% of the heat-related deaths reported in Maricopa County in 2023 involved drugs, alcohol or both substances, the report said. At least 4% of the cases involved people experiencing homelessness. 

Men made up more than three-quarters of the heat-related deaths, the data says. About two-thirds of the heat-related deaths were of people 50 and older. 

Heat is the leading weather-related cause of death in the United States, but its effects are sometimes underestimated because many people die of underlying conditions made worse by heat stress, such as heart attacks, respiratory problems or kidney disease.