Late-Season Monsoon Unleashes Widespread Flooding Across Southwest, Phoenix and Las Vegas Hit Hard

A powerful monsoon storm system swept through the Southwest on Friday, September 26, 2025. It unleashed torrential rains and severe thunderstorms, leading to widespread flooding across Phoenix and Las Vegas. The National Weather Service issued both flash flood warnings and a severe thunderstorm watch.

This was the first major storm of its kind for the region this late in the year. Officials expressed concern over hail, damaging winds, and rapid water accumulation. According to Fox News, the event caused significant travel disruptions.

Rainfall Disrupts Airports and Roadways

Phoenix Sky Harbor International Airport recorded nearly two inches of rain in a single day. This total exceeded the rainfall of the entire monsoon season so far. It also marked the wettest day in the city for seven years.

The National Weather Service in Phoenix posted a flash flood warning on X. The warning extended to Phoenix, Mesa, and Chandler until 6:00 PM MST. They emphasized that flooding was the most significant threat, despite reports of severe thunderstorms with hail.

Officials urgently warned motorists to avoid flooded roadways. They specifically highlighted dangers near creeks, streams, and other low-lying areas where water depth was unknown. The advice was to never attempt to drive through floodwaters.

Travel Chaos and a Fading Monsoon Season

The Federal Aviation Administration issued ground stops at airports in Phoenix and Las Vegas. According to Fox News, flight delays were estimated at one to two hours. Hundreds of flights were either canceled or diverted due to the extreme weather.

Thankfully, there were no immediate reports of missing persons linked to the storms. The National Weather Service confirmed the impacts, while severe, did not reach the level of a flash flood emergency. Such a designation is reserved for catastrophic, life-threatening events.

Meteorologists indicate this storm likely signals the end of the 2025 monsoon season. The season typically recedes by late September. The FOX Forecast Center predicts scattered showers over the weekend before drier conditions return.

This late-season event underscores the volatile nature of monsoon patterns. The significant Phoenix Las Vegas monsoon flooding serves as a stark reminder of the power of these weather systems. Residents are advised to remain cautious even as the storms subside.

Info at your fingertips-

What areas were most affected by the flooding?

The flash flood warnings specifically included Phoenix, Mesa, and Chandler. Regions outside Las Vegas were also significantly impacted by the heavy rainfall and resulting flood conditions.

How were major airports impacted?

Both Phoenix Sky Harbor International Airport and Las Vegas airports experienced major disruptions. The FAA imposed ground stops, leading to hundreds of flight cancellations and delays averaging one to two hours.

Was this event considered catastrophic?

No. The National Weather Service confirmed the flooding did not meet the criteria for a “flash flood emergency.” That classification is reserved for the most severe, life-threatening events, which this was not.

Is the monsoon season now over?

It is very likely. Meteorologists note that this storm signals the tail end of the monsoon season, which typically fades by late September. Drier conditions are expected to follow.

Why was the rainfall in Phoenix so significant?

The nearly two inches of rain recorded at Sky Harbor Airport made it the city’s wettest day in seven years. It also surpassed the total rainfall accumulated during the entire 2025 monsoon season up to that point.

Trusted Sources

National Weather Service, Fox News, FOX Forecast Center, Federal Aviation Administration (FAA).