Extreme heat warning issued ahead of historic 100-degree streak in Phoenix

PHOENIX – The first extreme heat warning of 2026 has been issued ahead of what’s expected to be a historic run of triple-digit temperatures in Phoenix.

A National Weather Service (NWS) warning for much of central and southern Arizona goes into effect Thursday morning and runs through Sunday evening.

Good afternoon, the Extreme Heat Watch has been upgraded to an Extreme Heat Warning for the later half of this week & this weekend. Temperatures will be 20-30° above normal and are forecasted to shatter daily records. Make sure to practice smart heat safety this week! #azwx #cawx pic.twitter.com/m2KJo7heC4

— NWS Phoenix (@NWSPhoenix) March 16, 2026

It’s the first extreme heat warning (or excessive heat warning, the term used until last year) ever issued in Arizona during the winter, which runs through March 20. In fact, an April 26-30, 2020, advisory was the only extreme heat warning issued earlier than May until now.

Extreme heat warnings trigger the daytime closures of some or all hiking trails at Camelback Mountain, Piestewa Peak and South Mountain in Phoenix.

Phoenix records expected to fall during extreme heat warning

Meanwhile, Tuesday, with a forecast high in the mid-90s, will probably be the last day of the week without daily-record heat.

With a projected high of 102 degrees, Wednesday is expected to be Phoenix’s first triple-digit day of the year and the hottest day ever recorded in March.

But that’s just the start of what could be a sustained stretch of record heat during a time when the normal high is about 80 degrees.

“Thursday and Friday, we’re looking at highs around 105, as high as maybe 107 Friday into Saturday. And by that point, with temperatures around 105 to 107, that’s more like 25 degrees above normal,” Chris Kuhlman, meteorologist with the NWS in Phoenix, told KTAR News 92.3 FM on Tuesday morning.

Kuhlman said Valley residents and visitors should prepare for temperatures in the 90s by late morning and triple digits in the afternoon during the heat wave.

Heat safety isn’t limited to the outdoors, be sure to keep yourself and others safe no matter where you are. If you have to be outside for extended periods, drink plenty of water, take breaks in the shade or in a nearby cool building, and limit strenuous activities. #azwx #cawx pic.twitter.com/G4ZpBV8d01

— NWS Phoenix (@NWSPhoenix) March 17, 2026

“Stay hydrated. If you don’t need to go outside during the hottest part of the day, don’t. Try to avoid it,” he said. “Wear plenty of sunscreen and ultimately just practice good heat safety.”

Until now, Phoenix almost never reached 100 degrees in March

Phoenix has recorded triple digits in the third month of the year only once before, when the high temperature was an even 100 degrees on March 26, 1988. The hottest temperatures of this week could even top the all-time April record of 105 degrees.

Temperatures will start to dip after peaking on Friday and Saturday, but highs are expected to remain at least in the upper 90s through next Tuesday, Kuhlman noted.

“And for the rest of next week it’s kind of hard to tell because it’s beyond our forecast period, but it will likely be at least … 10 degrees, maybe even 15 degrees, above normal all through next week as the pattern doesn’t really change all that much and we won’t see any significant cooling,” he said.

KTAR News 92.3 FM’s Gina McFarland contributed to this report.

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