Thunderstorms moved through the Tucson Metro area on the evening of September 18th and produced locally heavy rainfall that caused washes to flow with water. Two swift water rescues occurred along the Alamo wash due to people attempting to cross in their cars.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS TWC wrote it up.
Thunderstorms moved through the Tucson Metro area on the evening of September 18th and produced locally heavy rainfall that caused washes to flow with water. Two swift water rescues occurred along the Alamo wash due to people attempting to cross in their cars. In both cases, all of the people were rescued with no injuries. The thunderstorms produced outflow winds strong enough to loft areas of blowing dust along Interstate 10 from Picacho to Eloy and reduced visibilities to less than 0.25 miles.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Tucson, AZ wrote its last area forecast discussion before the first event at Sep 18, 3:16 PM MST, 3 hours 57 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Tucson AZ 316 PM MST Thu Sep 18 2025 .SYNOPSIS...Moisture has moved into the region which will lead to scattered showers and thunderstorms today and Friday with diminishing thunderstorm chances over the weekend. Temperatures near to just below normal into the weekend before warmer and drier weather returns next week. && .KEY MESSAGES... -Chances (30-50%) for isolated to scattered showers and storms forming primarily on the high terrain. Storms may linger into the evening and overnight hours. Localized instances of flash flooding possible. -Chances (30-60%) for scattered showers and thunderstorms tomorrow, mainly from Sells eastward. Localized instances of flash flooding possible if storms form or train over the same areas. A few storms may be strong with small hail and gusty winds. -Limited chances (10-20%) for a few isolated showers and thunderstorms into the weekend, but trending warmer and drier heading into next week with Tucson likely hitting 100 degrees by midweek. && .DISCUSSION...Storms so far have been struggling to form mainly over the higher terrain this afternoon. Later this afternoon and evening still thinking activity could increase in coverage though. The 18/18Z sounding at KTWC came back with 1200 J/kg of MUCAPE compared to about 450 J/kg yesterday. The added instability combined with the moisture already in place means it wouldn't take much lift to get storms going. However, the best dynamics have remained rather tight to the circulation in western AZ/southern CA/southern NV associated with the remnant low of Mario. While confidence is low that we will be able to tap into the better dynamics this afternoon, if storms are able to get going and grow upscale in coverage the environment is favorable for localized instances of flash flooding. Overnight, an upper jet will move into southeast Arizona potentially aiding convective development. Right now there is a 20-50% chance of storms continuing into the overnight period. Tomorrow morning we may see a ramp up in activity again after sunrise with even more robust development possible (30-60%) heading into the afternoon hours. This looks like a Type IV synoptic pattern setup with the trough/remnant low from Mario over the California coast advancing from the west and the Monsoon circulation sagging just to our south and east in Sonora Mexico. With plenty of moisture available to work with storms that do form could potentially grow upscale and be sustained. We'll need to continue to monitor how high resolution guidance is trending, but stronger storms could support gusty winds and small hail tomorrow in addition to localized flash flooding from backbuilding and training storms. Over the weekend residual moisture could fuel a few isolated pulse thunderstorms in the afternoon, but for now chances remain low (10- 20%) as we lose favorable dynamic support for additional storm coverage. Ridging begins to build back into southeast Arizona resulting in a warming and drying trend. Ensembles hint at an omega high blocking pattern setting up with a trough over southern California and another over the central plains supporting temperatures climbing above normal and trending much drier. This forecast package now has Tucson hitting triple digits again by midweek. && .AVIATION...Valid through 20/00Z. SCT-BKN clouds 6k-10k ft AGL and SCT-BKN layer AOA 18k ft AGL thru the valid period. Isolated to scattered TSRA through this afternoon and evening. Some overnight activity will be possible be confidence on terminals being affected is low. Gusty and erratic winds to around 35 kts possible near thunderstorms. Outside of thunderstorms, SFC winds SLY to SWLY at 5-10 kts through 19/03Z becoming variable less than 7 kts at other times. Tomorrow chances for scattered showers and thunderstorms continue through the day across southeast Arizona. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Above normal moisture is in place leading to min RH between 20-40 percent through the weekend. Expect scattered shower and thunderstorm chances (30-60 pct chance) today and Friday, then diminished thunderstorm chances this weekend. Heavy rainfall will be the main threat. Dry conditions return next week. 20-foot winds will be 8-12 mph with some afternoon/early evening gusts to around 20 mph over the next week with normal diurnal patterns through the weekend. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && DVS Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Preliminary Local Storm Report
National Weather Service Tucson AZ
330 PM MST Thu Sep 18 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0610 PM Flash Flood 5 WNW Tucson 32.23N 110.96W
09/17/2025 Pima AZ Public
Delayed report. Social media video of water
overtopping curbs west of university campus.
&&
AJEThe Tucson radar (KEMX), 38 km away, was scanning. The volume nearest the first event began at 02:10 UTC.
2 flash flood, 2 dust storm. Local standard time, as filed.
Swift water rescue at E Vernice St and Birch Ave along the Alamo Wash. Occupant rescued with no injury. A nearby rain gauge recorded 0.55 inches of water in 2 hours.
Swift water rescue at East Calle Bettelgeux Rd and South Avenida Planeta Rd along the Alamo Wash. Occupant rescued without injury. A nearby rain gauge recorded 0.55 inches of water in 2 hours.
Video on social media of near zero visibility along Interstate 10 from blowing dust.
Arizona Department of Transportation's dust sensor recorded 900 yards of visibility due to blowing dust at mile marker 213 on Interstate 10 near Picacho, AZ.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2025Every state in 2025This day in weather historyWarnings in Arizona, September 2025
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1295493, 1295495, 1295497, 1295506.