Flood watches take effect across southern and central Arizona today as moisture from Hurricane Polo feeds a Pacific storm system, raising the risk of flash flooding in metro Tucson from late Monday morning and in the Phoenix area from late Monday night. The watch for all of southeast Arizona, including metro Tucson, runs from 11 a.m. Monday through 11 p.m. Tuesday, KOLD reported.
For the Phoenix area, the National Weather Service's Phoenix office said its watch runs from late Monday night through Tuesday evening and covers higher terrain in central and eastern Arizona. In a forecast discussion issued Sunday afternoon, forecasters said the foothills and high terrain of Maricopa, Pinal, and Gila counties have the greatest chance of heavy rain, while moderate to heavy rain in the lower deserts is expected to be more localized.
The weather service expects the most active period overnight into early Tuesday morning, so rain could still be falling during the Tuesday morning commute in both metro areas.
Two Watches, Two Timelines Across Southern Arizona
Tucson residents face the longer window. KOLD reported that rain chances climb to 80% Monday night and again Tuesday for the metro area, with daytime highs falling into the low 80s by midweek.
In the Valley, AZFamily reported that the watch covers northern and eastern parts of the metro area, including parts of Scottsdale, Peoria, and Apache Junction. The station put the Valley's rain chance at a peak of 60% overnight into Tuesday morning.
The weather service said Tuesday is "shaping up to be the most interesting day of the next three" and that models are still not in full agreement on where the storm's center of circulation will be Tuesday morning. That position will help decide where additional rain falls. Forecasters also said some storms, particularly in the western deserts and Lower Colorado River Valley, could become strong enough to produce damaging winds and small hail.
MedicalDaily previously reported that Polo, then a Category 5 hurricane off Mexico, could send dangerous surf and rip currents to Southern California beaches. The threat has since moved inland. The Weather Channel reported that Polo was a 125-mph hurricane less than 300 miles west of Cabo San Lucas and was expected to make landfall along the Baja California coast Monday afternoon as its moisture streams north. The weather service and AZFamily said moisture from the remnants of Odalys is also feeding the system.
Washes, Underpasses, and Burn Scars Carry the Highest Risk
Flash floods in the desert do not require rain directly overhead. Storms upstream can send fast-moving water through dry washes, low-water crossings, and highway underpasses with little warning, and hard, dry ground absorbs little of it.
The weather service said abundant moisture and the potential for sustained storms "will also increase flooding risk Tuesday morning into the evening." Weather Channel forecasters have also flagged burn scar areas as a particular concern, because land stripped of vegetation by wildfire can shed water and debris quickly.
Drivers face the most common danger. The Weather Channel noted that water can enter a vehicle within minutes or even seconds once it drives into a flooded area, and water depth is hard to judge, especially at night. The standing safety advice is short: turn around, don't drown.
Forecast Totals Are Estimates, Not Measured Rain
No official rainfall totals from this event have been recorded yet. AZFamily's forecast calls for 0.25 to 1 inch across the Valley and 1 to 2 inches or more in the High Country. The weather service's forecast is more conservative for most areas, calling for a few hundredths of an inch up to half an inch, with locally higher amounts in the high terrain north and east of Phoenix.
Regionally, The Weather Channel said parts of the Southwest could see 3 to 5 inches of rain over the week, with some areas getting more than a month's worth of rain from this event. Arizona, New Mexico, and Texas face the greatest flash flood risk Tuesday, according to the outlet.
Those numbers can shift quickly. Small changes in where storms set up can decide whether a neighborhood gets a light soaking or a flooded street, which is why forecasters stress watching for warnings rather than relying on totals.
Protecting Commuters, Children, and Older Relatives Through Tuesday
A flood watch means conditions favor flooding. A flash flood warning means flooding is happening or about to happen, and that is the moment to avoid travel and move to higher ground if you are in a flood-prone spot.
Parents should remind children and teenagers to stay out of washes, drainage channels, and retention basins, which can fill quickly. Commuters can check routes before leaving Tuesday and allow extra time. Families caring for older relatives, or anyone who depends on powered medical equipment or refrigerated medications, should plan for possible power outages if strong storms develop.
Floodwater can contain sewage, hazardous waste, and debris, and eating or drinking anything contaminated by it can cause diarrheal illness, according to the Centers for Disease Control and Prevention. The agency advises people with open wounds to avoid floodwater and to cover wounds with a waterproof bandage.
The weather service said high pressure is forecast to move in Wednesday, bringing clearing skies and lower moisture, with highs topping 100 degrees in the western deserts by Thursday or Friday. Until then, residents should turn on local emergency alerts and treat every flooded road as impassable.
Sept. 28, 2026: Flood watches begin in southeast Arizona at 11 a.m. and in the Phoenix-area high terrain late Monday night.
Sept. 27, 2026: NWS Phoenix and Tucson offices issue flood watches as Polo moisture moves north.
Sept. 23, 2026: MedicalDaily reports Polo's surf and rip current threat to Southern California.
Key Questions Answered
When do the flood watches start? The southeast Arizona watch, including Tucson, runs from 11 a.m. Monday through 11 p.m. Tuesday. The Phoenix-area watch runs from late Monday night through Tuesday evening.
Which Phoenix-area communities are included? AZFamily reported that the watch covers northern and eastern parts of the Valley, including parts of Scottsdale, Peoria, and Apache Junction. The weather service said the foothills and high terrain of Maricopa, Pinal, and Gila counties have the greatest chance of heavy rain.
How much rain will fall? Forecasts range from a few hundredths of an inch to about 1 inch in the Valley, with more in higher terrain. These are forecasts, not measured amounts.
Is Hurricane Polo going to hit Arizona? Polo was expected to make landfall in Baja California. Its moisture, combined with a Pacific storm system, is driving Arizona's flood risk.
What is the biggest danger? Driving or walking into flooded washes, dips, and underpasses. Water can enter a vehicle within minutes or even seconds.
What should I do if a flash flood warning is issued? Avoid travel if possible, stay away from washes, and move to higher ground if you are in a flood-prone area.
Published by Medicaldaily.com
