Phoenix’s historically hot, dry September ends, but excessive heat stretches into October

PHOENIX – When they say it’s a dry heat in Arizona, they aren’t kidding. Monday was a perfect example.

It was the last day of the hottest September on record in Phoenix, and it put a cap on one of the city’s driest monsoon seasons ever.

“The average temperature for September this year was 94.6. That’s over 2 degrees warmer than the previous record, which was 92.2 in 2001,” Sean Benedict of the National Weather Service (NWS) in Phoenix told KTAR News 92.3 FM on Tuesday morning.

The average daytime high during Phoenix’s September was 106.6 degrees, and the average low was 82.5, Benedict said.

Phoenix’s hottest September followed its hottest June, second hottest July and third hottest August. Additionally, the 2024 “meteorological summer” (June-August) was the city’s hottest on record.

The high Monday at Phoenix Sky Harbor International Airport, which the NWS uses for the city’s official readings, was just above the monthly average at 107 degrees, tying the record for Sept. 30. And the morning low of 83 degrees set a new mark for warmest low temperature for the date.

Phoenix’s hottest September ends with record streak

While Monday only tied the previous high mark, Phoenix closed out its hottest September with seven consecutive days either matching or breaking the daily heat record. Looking ahead, the forecast calls for new record highs each day from Tuesday through at least Monday.

“This heat just doesn’t seem to want to end. It’s going to continue right … through at least the first week of October,” Benedict said.

The Phoenix meteorologist said a large ridge of high pressure is to blame for elevated temperatures in the western U.S. As a result, he added, the excessive heat warning currently in effect through Friday night for the Valley could be extended through the weekend.

Until the ongoing fall heat wave, the Phoenix area had never been under an excessive heat warning later in a year than Sept. 17, according to NWS records.

Tuesday, October 1, 2024. Unfortunately, we are starting out October with record warmth. The low temperature at Sky Harbor was 84 degrees, 12 degrees above normal. #azwx pic.twitter.com/YRNnFlki2G

— NWS Phoenix (@NWSPhoenix) October 1, 2024

Another heat milestone could be attained Tuesday. With a forecast high of 113 degrees, Phoenix is expected to break the daily record and reach at least 110 for the first time ever in October.

“It doesn’t look like the heat’s going to break until potentially next week,” Benedict said.

Monsoon 2024 finishes in top 10 for least rainfall

When it comes to precipitation, the 2024 monsoon season, which runs annually from June 15 to Sept. 30, went out with a whimper.

Sky Harbor received only a smattering of measurable rainfall over that span, most recently on Aug. 22.

Final day of Monsoon 2024 & 0.74" rainfall total at Sky Harbor airport ranked as 7th driest on record. Amounts in parts of West Valley were even lower (below 0.25") while some areas in Scottsdale and N. Phoenix got between 1.50" and 3.00" totals. #azwx pic.twitter.com/MgWssQdhfH

— NWS Phoenix (@NWSPhoenix) September 30, 2024

The annual “wet season” ended with Phoenix receiving a total of 0.74 inches of rain, making it the seventh-driest monsoon on record, per the NWS.

The monsoon totals were even lower in parts of the West Valley, but it ranged from 1.5 to 3 inches in areas of Scottsdale and north Phoenix, according to the NWS.

Historically, Phoenix sees 2-3 inches of monsoonal rainfall per year. 2023 was the driest monsoon season ever recorded in Phoenix, with a scant 0.15 inches.

“We just can’t seem to catch a break with all the heat and lack of rain during what should normally be our wet season. So, just a double whammy over the past several months,” Ryan Worley of the NWS told KTAR News on Monday morning.

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

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