From flash floods to wildfires, the summer monsoon brings a double-edged threat
In addition to flash floods and dangerous lightning, southwest monsoon storms can also spark wildfires.
Thunder roared as intense thunderstorms swept across the Southwest from Aug. 21-23.
After a relatively quiet monsoon season across the desert Southwest this summer, monsoon activity has picked up in recent weeks. On Sept. 4, Phoenix Sky Harbor recorded 0.18 of an inch of rain, while North Las Vegas recorded rainfall on Sept. 5 and 6. For context, the average monsoon totals are 5.69 inches in Tucson, 2.43 inches in Phoenix, 4.48 inches in Albuquerque and 5.27 inches in El Paso. Phoenix typically receives just over 7 inches of rain annually, so the summer monsoon is a critical source of precipitation.
Here's quick primer on monsoons: Often associated with heavy rain, the monsoon is really defined by a seasonal shift in wind direction. Some of the most notable examples occur in Asia and the Indian Ocean, where regions like Goa, India, go from nearly rainless winters to nearly 94 inches of rain between June and August.
The word "monsoon" comes from the Arabic for “season,” reflecting that it’s about more than just precipitation. "When the flow for a season switches from land to ocean in some monsoonal affected regimes, that flow delivers dry air from the continent leading to a 'dry' monsoon," AccuWeather Senior Meteorologist David Houk explained. "However, when the land is warmer than the surrounding ocean, the flow [comes] from the ocean to the land helping to deliver increased moisture to fuel the seasonal rains or 'wet' monsoon."
In North America, the monsoon brings moist air northward from Mexico, the Gulf of California and the tropical Pacific, fueling summer thunderstorms in cities such as Phoenix, Las Vegas and Albuquerque. Houk added that the North American monsoon typically begins in northwestern Mexico in June and expands northward into the southwestern U.S. in July before tapering off by the end of September.
A dust storm warning was put in place in Phoenix, Arizona, on July 21. Strong winds sent debris and dust into the air, as well as toppling trees.
Other monsoon hazards
Among the biggest dangers from monsoons is flash flooding. During monsoon season, intense rains can cause dangerous flooding because burn scars leave soil water-repellent and stripped of vegetation, causing rapid runoff and debris flows that threaten downstream areas. The blackened, altered soil no longer absorbs water effectively, leading to flash floods with less rainfall than usual—a risk that can persist for years after a wildfire as the landscape slowly recovers. Flash floods, not lightning, are the deadliest hazard linked to thunderstorms.
Another danger from the monsoon in the Southwest is lightning. In the especially active year of 2006, Arizona recorded more than 825,000 strikes, according to NOAA — far above the state’s average of just over 491,000. This year, by contrast, Arizona has recorded only about 131,000 strikes. Taken together, Arizona and New Mexico average more than 1.5 million lightning strikes annually, accounting for over 15% of all strikes in the lower 48 states.
Wildfire risks
In this handout image provided by Grand Canyon National Park, The Dragon Bravo Fire is seen at Grand Canyon National Park on July 11, 2025. The fire is located on the North Rim of the park and is estimated at 1,500 acres. Due to increased fire activity, mandatory evacuation orders were issued earlier today for North Rim residents. (Photo by Grand Canyon National Park via Getty Images)
About half of all of all wildfires reported in the Southwest over the past decade have been lightning caused. The Dragon Bravo wildfire at the Grand Canyon's North Rim, which started all the way back on July 4 and continues to burn, was started due to a lightning strike. The fire, currently at 80% containment, recently took the life of a firefighter and has destroyed more than 100 buildings, including a historic lodge and burned through nearly 150,000 acres.
A dramatic pyrocumulus cloud, or fire cloud, formed as the large Dragon Bravo Fire burned along the Grand Canyon’s North Rim in Arizona this week.
The Dragon Bravo Fire illustrates the dangers of lightning during monsoon storms. The North Rim of the Grand Canyon experienced just half its normal monsoon rainfall in summer 2024 and only 50% of average snowfall in winter 2024–2025. Prolonged drought, low humidity, record-high temperatures and strong afternoon winds created extreme fire conditions. Critically low live and dead fuel moisture, combined with delayed monsoon activity, allowed the Dragon Bravo Fire to spread rapidly across the North Rim.
Fires during monsoon season often ignite from dry lightning storms when little or no rain falls. In other cases, a lightning strike can smolder for days—even after some precipitation—before growing into a wildfire.
Other recent lightning-sparked wildfires in the region include the South Fork Fire in New Mexico in June 2024. A lightning strike ignited this fire, which burned over 15,000 acres and destroyed or damaged more than 1,400 structures in the mountain village of Ruidoso. At least two fatalities were reported. Even after the fire reached 99% containment by July 15, the area experienced post-fire flooding caused by heavy rainfall over the burn scar.
If you’re in an area burned by wildfires, your risk of flooding will skyrocket for years to come, as the recent devastation in New Mexico unfortunately shows.
And back in June 2002, the Ponil Complex Fire in New Mexico burned a total area of 92,470 acres, including areas in the Valle Vidal unit of Carson National Forest. It was the largest wildfire of its time in New Mexico.
As the Southwest monsoon unfolds each summer through Sept. 30, it continues to bring both relief and risk to the region.
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