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Q&AZ: Is Arizona Getting Hotter?

Via Q&AZ, KJZZ listeners Sarath Joshua and Tabitha Myers asked if Phoenix has been experiencing increasingly hotter summers.

Nancy Selover, the climatologist for the state of Arizona, said without a doubt: Yes.

“Phoenix summers are getting hotter and Phoenix winters are also getting hotter,” she said. “But it’s not necessarily that the high temperatures of the day are getting much hotter than they used to.”

While temperatures above 110 raise eyebrows, the highs in Phoenix haven’t changed that much in the last 70 years.

The nighttime temperature — or the average lowest temperature — is the best indicator of overall change, Selover said.

According to data from the National Weather Service, the nighttime low has increased about seven degrees in Phoenix since the 1940s.

Selover attributed the majority of that change to more commercial and residential developments retaining the heat.

“We have now changed from being irrigated agriculture scattered around the city to replacing all that irrigated agriculture with pavements and houses and tile roofs and streets and things like that,” she said.

However it’s not all development. Historic temperatures at Casa Grande National Monument — which has not seen development like Phoenix — has risen about 2.5 degrees since the 1940s.

Selover said that increase — which is calculated over many decades and takes weather patterns into account — proves that climate change is also pushing up the barometer.

Claire Caulfield was a reporter and Morning Edition producer from 2015 to 2019.