Phoenix forecast calls for earliest 100-degree day on record

PHOENIX – If the temperature hits 100 degrees in Phoenix on Tuesday, as expected, it wouldn’t just be the first day in triple digits for 2025.

“That would be the earliest 100 degrees on record for Phoenix … by one day, because the earliest on record is March 26. That was all the way back in 1988,” Matt Salerno of the National Weather Service in Phoenix told KTAR News 92.3 FM on Tuesday morning.

The average date for Phoenix’s first triple-digit day of the year is May 2.

“Obviously, we’re accustomed to 100-degree temperatures. But … it’s definitely a little bit early,” Salerno said.

Another day of record breaking heat is expected with highs approaching the century mark in the lower deserts. If we reach the forecast high of 100 degrees in Phoenix, it would be the earliest occurrence on record. Temps will slowly cool through the rest of this week. #azwx #cawx pic.twitter.com/VswWM7sZRZ

— NWS Phoenix (@NWSPhoenix) March 25, 2025

Even if Tuesday’s high falls just shy of the century mark, Phoenix will most likely set a daily heat record for the second consecutive day. The record for March 25 is 96 degrees from 2022.

It reached 96 degrees in Phoenix on Monday, surpassing the previous high for March 24 of 94 degrees, which was set back in 1990.

Why is Phoenix on verge of 100 degrees so early?

Salerno said temperatures are running far above normal this week due to a strong ridge of high pressure in the upper atmosphere.

“What that’s doing is just basically keeping our sky cloudless … and helping us to heat up a lot more efficiently across the lower deserts,” he explained.

The system is making an impact beyond the Valley, too.

“It’s encompassing the entire desert Southwest, so it’s not only Phoenix that’s going to be seeing these record high temperatures,” Salerno said. “Yuma and places to our west are also going to probably be experiencing near-record highs today and tomorrow.”

How long will spring heat wave last in Phoenix?

The unusually warm Phoenix temperatures are expected to last a few more days, but below record levels after Tuesday.

“It does look like it’s going to cool down … heading through the rest of this week,” Salerno said. “But it’s going to be a slow process getting down back down into the 80s, probably not until Friday. … But by this weekend, we should be back down to more of the normal lower 80s that we should be seeing this time of year.”

KTAR News 92.3 FM’s Colton Krolak contributed to this report.

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