Maricopa County health officials reported the first year-over-year decline in heat-related deaths since 2014 but cautioned Valley summers remain a danger.

The Maricopa County Department of Public Health has released its 2024 preliminary report on heat-related deaths showing 602 confirmed deaths attributed to environmental heat, with eight deaths remaining under investigation. 

It marks the first year-over-year decrease in heat deaths since 2014, down from the record-breaking 645 deaths in 2023, despite being the hottest summer on record.

“While this reduction in heat deaths is a step in the right direction, we need to continue educating residents about the dangers of extreme heat and the steps they can take to stay safe and protect their loved ones,” Maricopa County Board of Supervisors Chairman Thomas Galvin said.

Each death is a preventable tragedy, and Maricopa County remains committed to working with our community partners to reduce the number of heat-related deaths further.”

In 2024, Maricopa County experienced an unprecedented heat season, with the Phoenix metro region enduring 113 consecutive days of temperatures at or above 100 degrees Fahrenheit from May 27 to Sept. 16, according to a release.

“While all residents and visitors of Maricopa County are affected by extreme heat, people experiencing homelessness, older adults and people who use substances are among those most impacted. Among the 349 heat-related deaths involving substances in 2024, 89% involved stimulants,” the release stated.

“We know that heat is a force multiplier for many underlying health conditions, including substance use disorders, heart disease and the effects of medications that alter the body’s response to heat,” said Dr. Nick Staab, chief medical officer for MCDPH.

“Prolonged exposure to heat can significantly worsen a person’s symptoms such as dehydration and increased heart rate, potentially leading to severe complications, including death.”

Additional preliminary report findings include:

• From June 18 to July 31, at least one heat-related death occurred every day in Maricopa County. During the 44-day period, 14 excessive heat warnings were issued, and 14 high temperature records were broken.
• More than half of all heat-related deaths in 2024 occurred on days when heat risk was calculated as moderate. 
• Among indoor deaths, 88% had air-conditioning units present, but 70% of those A/C units were not working.

In 2025, MCDPH will continue supporting prevention and response efforts aimed at addressing gaps and barriers to heat relief resources, the release stated.