Here’s why a veteran Arizona climate expert is alarmed by Phoenix’s relentless summer heat

PHOENIX – A longtime Arizona climate expert said he’s alarmed by the Phoenix summer heat this year, and it’s not just the relentless high temperatures that worry him.

“What I find most interesting, and kind of most ominous, is the low temperatures. We are not seeing the low temperatures getting down into what we would consider to be normal summer range,” Randy Cerveny, a professor of geographical sciences at Arizona State University since 1986, told KTAR News 92.3 FM on Wednesday.

Cerveny said it’s not just urban areas like Phoenix that are experiencing unprecedented summer heat, so it can’t be fully blamed on the heat island effect.

“Something beyond the urban heat island is also impacting that, and that’s climate change,” he said.

No breaks from Phoenix summer heat this year

The temperature at Phoenix Sky Harbor International Airport, which the National Weather Service uses for the city’s official readings, has reached at least 100 degrees every day since May 26. The record-shattering streak reached 102 days on Thursday, and there is no end in sight.

Thursday also was Phoenix’s 56th day of 2024 with a high of at least 110 degrees, a new record.

With an excessive heat warning in effect until Friday night, the record numbers are likely to grow.

Temperatures today will be the hottest out of the next several days, with afternoon highs hovering around 10 degrees above normal. A slight "cooldown" will take place by this weekend, but unseasonably hot conditions are expected to persist into next week. #azwx #cawx pic.twitter.com/P8Q0qHGmlR

— NWS Phoenix (@NWSPhoenix) September 5, 2024

Consistently warm low temperatures are contributing to the extreme Phoenix summer heat, Cerveny said.

“We’ve been, so far this summer, having lots of temperatures where the minimum temperature at the start of the day is in the 90s, and that’s alarming. That’s a good indication that something is actually happening to our climate,” Cerveny said.

Phoenix just completed its hottest meteorological summer (June-August) ever recorded, averaging 98.9 degrees, shattering the record of 97 degrees from 2023.

“When you average them all up, things like just a hundredth of a degree make a big difference as to climate state,” Cerveny said. “So, when we’re seeing changes that are 1, 2 degrees above the average, that’s a substantial change meteorologically, and it’s something we have to be worried about.”

KTAR News 92.3 FM’s Jim Cross contributed to this report.

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