Extreme Heat Grips Phoenix Through Tuesday As Storm Chances Return

PHOENIX, AZ — The Valley's heat wave is far from finished.

An Extreme Heat Warning remains in effect for Phoenix through Tuesday as temperatures continue climbing into the 110- to 116-degree range. Forecasters say the start of the week could also bring gusty outflow winds, blowing dust and a slight chance of storms.

According to the National Weather Service, the stubborn "heat dome" parked over the Southwest remains firmly in place, even as the high-pressure system fueling it begins to weaken.

Even so, relief will be limited. Highs are still expected to top 110 degrees through Tuesday, while rising humidity pushes afternoon heat index values into the 110- to 115-degree range.

The bigger concern Monday may not be rain, but wind.

As monsoon moisture spreads across southern Arizona and the atmosphere becomes more unstable, forecasters say strong outflow winds and blowing dust are more likely than widespread thunderstorms in the Phoenix area.

Computer models suggest a surge of wind could sweep into Pinal and Maricopa counties Monday evening, bringing gusts of more than 35 mph and the potential for reduced visibility in areas affected by blowing dust.

A strong layer of warm air overhead is expected to keep most storms from developing directly over the Valley, but forecasters aren't ruling them out entirely.

Phoenix has about a 10% chance of seeing a shower or thunderstorm between 9 p.m. and shortly after midnight Monday.

The greatest storm chances remain over Arizona's higher terrain, especially the White Mountains and southeastern Arizona, where thunderstorms could produce locally heavy rain. While the overall flood threat is low, an isolated storm could still trigger localized flooding.

Tuesday's forecast will depend in part on how Monday night's weather unfolds. Another round of afternoon and evening thunderstorms is expected across east-central and southeastern Arizona, with another outflow boundary potentially reaching the lower deserts by Tuesday evening.

Looking beyond Tuesday, don't expect much relief.

Hot and increasingly humid conditions are expected to persist through the second half of the week. National Weather Service forecasters say the current Extreme Heat Warning will likely be extended beyond Tuesday for much of south-central Arizona. Wednesday's high in Phoenix is forecast between 107 and 110 degrees, with heat index values once again climbing into the 110- to 115-degree range.