On the final day of summer, the Pima County Sheriff’s Department reported the death of a 69-year-old hiker in Catalina State Park.
The incident underscores the risks that can remain for people spending time outdoors, even as autumn begins and temperatures begin to fall.
So when does Arizona’s heat actually become less dangerous?
The answer is not simply when temperatures fall below 100 degrees.
That cooling trend can reduce the risk of heat-related illness, but meteorologists say people should continue paying attention to both daytime and nighttime temperatures.
“The cooler time is in the morning – early morning hours before the sun really comes up by 10 or 11 in the morning,” says Kevin Strongman, a meteorologist with the National Weather Service. “The hottest part of the day is between 10 to about 4 each day – as we get closer to fall, the hours where sunlight gets a little smaller each day. We used to have 12 hours of sunshine. Now it's getting closer to close to 10 hours.”
According to the Pima County Health Department, 2026 is the warmest year on record for average high temperatures in Pima County.
As of Sept. 8, the county had reported 123 heat-related deaths — six more than the 117 deaths reported during all of 2025.
Seven heat-related deaths were reported between March and May alone.
According to the Pima County Health Department, heat-related ER visits are at 35.7 per 100,000 people in the county, while the state has 35.6 visits per 100,000.
And while temperatures are now trending downward, the National Weather Service says people should continue taking precautions in the heat, particularly when exercising or spending extended periods outdoors.
The combination of daytime temperatures, overnight lows, humidity, activity level and a person’s individual circumstances can all affect the risk.
Forecasters expect temperatures to be mostly in the 90s, with some upper-80s possible by October.
But for hikers and others spending time outdoors, precautions are still important.
“For hikers, make sure you have plenty of water, fluids, and make sure you hike with a buddy,” Strongman says. “Stay aware of the latest forecast for temperatures, but also for showers and thunderstorms. They do impact your hiking experience.”
Overnight temperatures are also important.
Cooler nights give the body an opportunity to recover from daytime heat. As temperatures move into the 70s and eventually the 60s overnight, the heat burden generally becomes easier to manage.
The Pima County Health Department says it continues working with community partners through the Heat Relief Network to provide heat-relief services to people vulnerable to extreme temperatures.
