Weather
Arizona Flood Watch: Flash Flood Threat Grows Oct. 21-22
Phoenix, AZ – A developing storm system is bringing a significant flooding threat to the Phoenix metropolitan area Wednesday, October 21, with thunderstorms, heavy rainfall and potentially dangerous r
By Lena Wood · 2026-10-21T10:33:27.044Z
Phoenix, AZ – A developing storm system is bringing a significant flooding threat to the Phoenix metropolitan area Wednesday, October 21, with thunderstorms, heavy rainfall and potentially dangerous runoff expected across portions of Maricopa County through Thursday afternoon. Residents throughout the Valley should prepare for changing road conditions as the strongest storms move through south central Arizona.
According to the National Weather Service in Phoenix, a Flood Watch remains in effect from 2 p.m. Wednesday until 5 p.m. Thursday. Forecasters warn that excessive rainfall could trigger flash flooding in washes, creeks, streams and low lying areas, particularly where thunderstorms repeatedly affect the same locations.
The watch covers a broad portion of the Phoenix metropolitan area, including Phoenix, Scottsdale, Mesa, Glendale, Chandler, Tempe, Gilbert, Peoria, Surprise and surrounding communities. Additional areas of Pinal County, including Apache Junction and Casa Grande, are also included.
Heavy Rain Could Create Dangerous Conditions The National Weather Service says a strong weather system will bring widespread showers and thunderstorms beginning Wednesday afternoon and continuing into Thursday evening.
Localized rainfall rates approaching 1 to 2 inches per hour are possible during stronger thunderstorms. Such rainfall intensity could overwhelm drainage systems and rapidly flood normally dry washes.
The threat is particularly important for motorists traveling near the New River, Skunk Creek and other flood prone waterways.
An early Wednesday Flood Advisory for portions of Maricopa County, effective until 3:45 a.m., also identified minor flooding concerns around New River and Skunk Creek. That advisory was separate from the longer duration Flood Watch.
Phoenix Five Day Weather Outlook Wednesday 10/21: Showers and thunderstorms become more likely during the day, especially after 8 a.m. Phoenix reaches approximately 86 degrees, with a 50% precipitation chance. Overnight thunderstorms remain likely, with a 60% chance of precipitation and temperatures falling near 72 degrees.
Thursday 10/22: Showers and thunderstorms remain likely, particularly before 2 p.m. The high reaches approximately 82 degrees, with a 60% precipitation chance. Conditions begin improving Thursday night, with partly cloudy skies and a low near 66 degrees.
Friday 10/23: Sunshine returns across Phoenix as the storm system moves away. Afternoon temperatures reach approximately 78 degrees, followed by mostly clear conditions and an overnight low near 63 degrees.
Saturday 10/24: Sunny skies continue across the Valley, with afternoon temperatures near 78 degrees. Mostly clear weather is expected Saturday night, with temperatures falling to approximately 62 degrees.
Sunday 10/25: Another sunny day is forecast, with afternoon temperatures near 80 degrees. Mostly clear conditions continue Sunday night, with a low around 63 degrees.
Longer Range Outlook Signals More Moisture NOAA's Climate Prediction Center outlook for October 28 through November 3 favors above normal precipitation across Arizona, suggesting the region could remain in a wetter than usual pattern late in October.
The same outlook indicates temperatures generally leaning above normal across portions of southern Arizona. These outlooks describe probabilities over a multiday period and do not guarantee additional storms or flooding in Phoenix.
What Residents Should Know The National Weather Service urges residents to monitor forecast updates and remain prepared for Flash Flood Warnings if conditions worsen.
Drivers should never attempt to cross flooded roads. Water can conceal damaged pavement, and even relatively shallow moving water can carry vehicles away.
Residents can monitor official alerts at weather.gov/psr as the storm system moves across the region.