Valley forecast starts with excessive heat warning followed by chance for storms midweek

PHOENIX – The Valley weather forecast for this week starts with potentially dangerous heat before shifting to the possibility for more thunderstorms.

The National Weather Service (NWS) issued an excessive heat warning in metro Phoenix for 10 a.m. Monday to 8 p.m. Tuesday.

An Excessive Heat Warning goes into effect at 10AM MST for portions of south-central AZ and continues through tomorrow evening. Remember to stay hydrated and limit your time outdoors, especially during the hottest time of the day. #azwx pic.twitter.com/8lE28HM3M8

— NWS Phoenix (@NWSPhoenix) August 19, 2024

NWS meteorologists issue excessive heat warnings to alert the public about extremely dangerous heat conditions.

Heat warnings are based on a variety of factors, not just temperature, and the standards can differ by location. High temperatures are expected to range from 107 to 114 degrees across south-central Arizona on Monday and Tuesday.

People who have to spend time outdoors during periods of excessive heat should stay hydrated, apply sunscreen to exposed skin, wear loose-fitting clothing and take frequent breaks in the shade, according to experts.

Per city of Phoenix policy, the Echo Canyon and Cholla trails at Camelback Mountain and all Piestewa Peak trails are closed from 9 a.m. to 5 a.m. on days when excessive heat warnings are in effect.

After excessive heat warning, Valley weather forecast includes rain chances

After this week’s hot start, another round of monsoon activity could hit the area Wednesday and Thursday, with a 30-40% chance for thunderstorms.

“And then it looks like we will likely dry out again by Friday and into next weekend,” Mark O’Malley of the National Weather Service in Phoenix told KTAR News 92.3 FM on Monday morning.

The swings in this week’s Valley weather forecast follow a widespread rain event over the weekend.

Most of metro Phoenix saw between 0.1 and 0.4 inches of rainfall, although some areas received more than an inch.

“I would say probably the most widespread event we’ve had so far the monsoon season,” O’Malley said.

Sunday’s storm limited Phoenix’s peak temperature to 102 degrees, 3 degrees below normal and the lowest high since it was also 102 on May 27.

Here is today's high temperature of 102 degrees which is 3 degrees below the normal. Today's high temperature is also the coolest its been since May 27th. #azwx pic.twitter.com/F9yYIeQKhb

— NWS Phoenix (@NWSPhoenix) August 19, 2024

However, the city’s record-setting streak of triple-digit days, which started on May 27, hit 84 days and counting on Sunday. The previous record of 76 days was set in 1993.

How much has it rained in Phoenix this monsoon season?

Phoenix Sky Harbor International Airport, which the National Weather Service uses for the city’s official readings, recorded 0.1 inches on Sunday. It was the most rain at the airport since July 14, when 0.33 inches fell.

Phoenix typically sees 2-3 inches of rain during the monsoon season, which runs annually from June 15 to Sept. 30. 2023 was the city’s driest monsoon season on record, with just .15 inches.

This year, Phoenix has recorded 0.50 inches since the monsoon season started.

“That’s a lot better than we did last year, but we do have some catching up to do, for sure, for the monsoon season, and plenty of time to do that,” O’Malley said.

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

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