Hurricane Polo could boost final few days of Tucson monsoon

Tucson could finish the 2026 monsoon season with more rain than usual as moisture connected to Hurricane Polo moves north from Mexico and the Gulf of California. Polo is not expected to reach Tucson directly, but National Weather Service forecasters say its moisture may strengthen an incoming weather system, bringing widespread showers, thunderstorms, strong winds and a heightened risk of flash flooding across the region during the final days of the season.

The storm’s influence could arrive from Sunday evening through Wednesday morning, when forecasts call for roughly 1 to 1.5 inches of rain across the Tucson area. The heaviest rainfall is expected Monday into Tuesday as deeper tropical moisture moves in. Dalton Van Stratten, a National Weather Service meteorologist, said Friday that the Tucson area faces a slight risk of flash flooding Monday and a marginal risk Tuesday. Isolated thunderstorms could also produce wind gusts exceeding 50 mph, a concern for drivers, pedestrians, outdoor businesses and neighborhoods vulnerable to runoff and falling trees.

That forecast comes after a monsoon season that has already brought several damaging storms to Tucson. A late August storm knocked down trees in Armory Park, including one near the recently completed dog park entrance that damaged new fencing and landed on parked cars. Cleanup crews worked through the following morning, while Tucson Electric Power crews repaired snapped lines near North Oracle Road. Storms have also sent pedestrians wading through flooded intersections, blown down an outdoor tent at The Hut on North Fourth Avenue and pushed water through streets near Fourth Avenue and Sixth Street. The Santa Cruz River has visibly risen after major rainfall events.

Polo rapidly intensified in the eastern Pacific, changing from a tropical depression to a Category 5 hurricane in a 24 hour period, according to the National Hurricane Center. Its maximum winds reached about 180 mph, and the storm fluctuated between Category 4 and Category 5 strength while bringing heavy rain and strong winds to coastal Mexico. Forecasts show the hurricane moving northwest, away from southwestern Mexico, before turning north toward the northwest coast and eventually approaching the Baja California Peninsula.

Forecasters expect Polo to weaken quickly as it crosses Baja California and moves into mainland Mexico. Even as the hurricane itself loses strength and remains far from Tucson, moisture associated with the storm is expected to travel into the southwestern United States over the weekend and early next week. Van Stratten said Tucson will not experience Polo’s direct impacts, but the moisture surge could supply energy to another weather system already moving toward the area. That combination is what could create heavier rainfall rates and more active storms locally.

The timing is significant because Tucson’s monsoon season officially runs from June 15 through Sept. 30. As of Friday morning, Tucson International Airport had recorded 5.38 inches of monsoon rainfall, just short of the 5.69 inch normal total. If the incoming system produces the forecast amounts, the city could move above its typical seasonal rainfall. This would also mark a substantial improvement over 2025, when the airport recorded only 2.82 inches during the monsoon.

The season began strongly. The first storm arrived on June 15 and produced 0.4 inches of rain, breaking the daily rainfall record for that date and helping make June the 11th wettest June on record, according to the National Weather Service. July then turned notably dry, with only 0.7 inches, less than one third of the normal 2.21 inches. August rebounded with 3.21 inches, above average. In total, Tucson recorded rain on 22 days, with the wettest day coming Aug. 31, when 0.84 inches fell.

Rainfall has varied across the region, with Nogales, Safford, Sierra Vista, Willcox and Picacho Peak recording totals close to or above normal. The Tucson metropolitan area also recorded about 5,400 lightning strikes since June 15 as of Wednesday. That was considerably more than the 3,117 strikes recorded during the same period last year, though still below the average of 7,699. Residents may see another dramatic round of lightning and storm clouds, like those that have recently illuminated the Catalina, Rincon and Santa Rita mountains, but the main concern will be the hazards arriving with the rain.

For people in Tucson, the forecast means the end of monsoon may bring both welcome water and serious risks. Heavy bursts can quickly flood roads, washes and low intersections, while strong winds can bring down branches, trees, tents and power lines. Residents should monitor updated forecasts through early next week, especially during the periods of heaviest rain Monday and Tuesday. If the moisture from Polo reaches the region as expected, Tucson could close out a stormy and uneven monsoon with a wetter than normal total.