As of 7:30 p.m. Friday, Sept. 25, 2026: Tropical moisture could bring rain and strong thunderstorms to the West Valley on Monday and Tuesday, according to a newly updated National Weather Service forecast. Forecasters caution that rainfall totals and the risk of severe weather remain uncertain.
Saturday is expected to stay dry and warm. Clouds should increase Saturday night into Sunday as moisture from the remnants of Tropical Storm Odalys spreads across Arizona. A few sprinkles could begin Sunday morning, followed by a narrow band of light rain somewhere in the region Sunday evening.
The more consequential period may begin Monday morning. The National Weather Service’s 5:13 p.m. forecast discussion gives the western deserts a 30% to 50% chance of rain Monday. Chances rise to 50% to 75% from Phoenix northward and eastward. Rain and isolated thunderstorms could continue Monday night before tapering from west to east Tuesday.
What the main forecast scenario shows
Forecasters assign about a 60% chance to their main scenario: a seasonably strong upper-level weather system moves through Arizona while pulling in enough moisture for widespread rain. Under that outcome, lower-desert rainfall would generally total 0.10 to 0.30 inch, while higher terrain north and east of Phoenix could receive 0.5 to 1 inch.
The setup could also produce a period of strong thunderstorms because winds are expected to change speed and direction with height. The Weather Service has not issued a watch or warning for the West Valley, and the forecast does not mean every community will receive the same amount of rain.
The agency gives a roughly 20% chance to a weaker or faster-moving system that would keep lower-desert totals below 0.25 inch. It assigns another 20% chance to a wetter, slower scenario. That outcome could bring 0.2 to 0.5 inch to the western deserts, including parts of western Maricopa County, and 0.75 to 1.5 inches across the south-central Arizona lower deserts. Strong to severe storms would be possible in that higher-end scenario.
Hurricane Polo is not expected to hit Arizona directly
Hurricane Polo is forecast to approach southern Baja and then weaken rapidly over southern Sonora, Mexico. The Weather Service said it does not expect direct impacts from Polo in Arizona. The storm may still help steer additional low- and mid-level moisture north into the state, increasing rain potential when the upper-level system arrives.
The amount and placement of that moisture remain the biggest forecast questions. A shift in Polo’s track or in the approaching weather system could materially change West Valley rain chances and totals.
Temperatures should fall as clouds and rain chances increase. Phoenix-area highs could drop into the mid-80s during the first half of next week, while the western deserts may remain in the low to mid-90s.
What West Valley residents should watch
Residents with outdoor plans should expect forecast changes through the weekend. Strong storms can produce lightning, gusty winds, blowing dust and localized flooding even where overall rainfall totals stay modest. Drivers should not enter water covering a road.
The Weather Service said it expects a clearer picture of potential impacts within a day or two. Current forecasts and any watches or warnings are available from NWS Phoenix. West Valley Post will update this story if the outlook changes materially.
Image: AI-generated editorial illustration. It does not depict a specific storm or location.
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