Thunderstorms with potential to produce flash flooding expected in Phoenix area this week

A major weather disturbance capable of producing severe thunderstorms and flash flooding is expected to hit the Phoenix area this week.

After a cloudy weekend with gusty winds and scattered showers, the forecast for Monday and Tuesday calls for mostly sunny skies with high temperatures near 90 degrees.

However, a strong Pacific low-pressure system is expected to move into the Valley late Tuesday or early Wednesday.

“That, combined with well above-normal moisture that’s going to be moving in, is actually going to instigate multiple rounds of showers and thunderstorms across much of south-central Arizona as we head into Wednesday and Thursday,” Gabriel Lojero, a meteorologist with the National Weather Service in Phoenix, told KTAR News 92.3 FM on Monday morning.

A low pressure system affecting the region midweek will bring a heightened chance for showers and storms across south-central and eastern AZ. Heavy rainfall leading to flash flooding and a few strong to severe storms leading to strong winds and hail are on the table. #azwx pic.twitter.com/JMbkxf46gm

— NWS Phoenix (@NWSPhoenix) October 19, 2026

Lojero said an increase in atmospheric instability could set off thunderstorms with heavy rainfall.

“We could be talking about these thunderstorms containing rainfall rates in excess of 1 to 2 inches per hour,” he said.

Areas hit by multiple rounds of storms could experience flash flooding, Lojero warned. Additionally, isolated severe thunderstorms could produce strong winds and hail.

Where is the greatest risk of flooding during this week’s thunderstorms?

“The highest rainfall amounts are going to be just to the north or northeast of Phoenix across the higher terrain areas. Those areas can actually see multiple inches of rain. So, the flash flooding risk could actually be greater up there, but [we] cannot rule out flash flooding here in the Phoenix metro,” Lojero said.

Lojero said the storms are expected to clear out before the weekend.

“By Friday, we’ll actually see improving weather conditions, drier conditions, and that should continue into next weekend,” he said.

The storm activity is expected to drop high temperatures below normal for this time of year.

“In fact, we might see highs that struggle to reach 80 degrees by Thursday and Friday,” Lojero said.

KTAR News 92.3 FM’s Martha Maurer contributed to this report.

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