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Q&AZ: When do triple-digit temperatures usually end in Phoenix?

Yellowed leaves silhouetted in the sun.
Chelsey Heath/KJZZ
Yellowing citrus tree leaves from the heat in the West Valley on Aug. 16, 2023.

This week’s rain brought some below-normal temperatures to the Valley. So are we almost done with triple-digits for this year?

Normal high temperatures in Phoenix for early September are in the low 100s and that’s about what’s expected for the next week, according to the National Weather Service.

This summer has been one of the hottest on record in Phoenix. So far in 2025, Phoenix has had 103 days in the triple-digits — that’s more than normal for this time of year. But, in total, Phoenix typically gets 111 days per year in the 100s, so we have not reached that yet.

National Weather Service

The earliest Phoenix has ever said goodbye to the triple digits was Sept. 2, back in 1904.

But climate change has caused hot temperatures to stretch later into fall in recent decades. Last year, Phoenix endured its hottest September and October on record, with temperatures above 110 lasting until Oct. 7.

On average since the 1990s, the last 100-degree day of the year in Phoenix has fallen around Oct. 5. The latest triple-digit day ever in Phoenix was Oct. 27, in 2016.

National Weather Service
Latest on Arizona heat

Katherine Davis-Young is a senior field correspondent reporting on a variety of issues, including public health and climate change.