Wildfire burn scars could trigger another natural disaster in Southern California
California is still reeling from wind-driven wildfires that raged through the Los Angeles area, but a shift in the weather could set off another life-threatening danger.
Rain drenched parts of Southern California over the weekend, causing mudslides and debris flows in areas scorched by recent wildfires.
Wildfires can decimate thousands of acres in a matter of hours, laying waste to huge swaths of land and destroying virtually everything in their path. However, when the flames are extinguished and the dust settles, the region can be at a higher risk of another natural disaster.
Areas scorched by wildfires are called burn scars--charred earth that is suddenly devoid of healthy, living plants, and these two ingredients can set the stage for a flooding disaster when heavy rain falls.
This is the concern across Southern California following the deadly Palisades Fire and Eaton Fire, which together burned more than 35,000 acres in the Los Angeles area.
Rain drenched parched Southern California over the weekend, with between 1 and 2 inches falling in some of the mountainous areas surrounding Los Angeles. Several mudslides were reported, including in Topanga Canyon, where mud, rock and debris flowed down a hillside.
Burned trees from the Palisades Fire are seen from Will Rogers State Park, with the City of Los Angeles in the background, in the Pacific Palisades neighborhood on January 15, 2025 in Los Angeles, California. (Photo by Apu Gomes/Getty Images)
The scorched earth acts more like pavement than typical soil, so instead of being absorbed by the ground, rain runs off the land and races downhill. Without a healthy root system from plants to help stabilize the ground, the landscape can be washed away, resulting in debris flows, mudslides and flash flooding.
"The force of this rushing water and debris can also damage or even destroy things like culverts, bridges, roadways and even buildings that were left standing after the fires -- even miles away from the burned area," AccuWeather Broadcast Meteorologist Damien Lodes explained.
The area in and downhill of burn scars can be susceptible to flash flooding and debris flow for several years following a fire as it takes the land time to recover and plants to grow.
Flooding risk in Los Angeles area following large wildfires
Heavily populated areas could be at a heightened risk of flooding and mudslides in Southern California in the coming weeks and months due to how close some fires burned to neighborhoods.
"Debris flows and mudslides, and the nature of the area around Altadena, it's uphill from so many other populated areas above Pasadena, for example," AccuWeather Assistant Chief Video Meteorologist Geoff Cornish explained. "When we do see heavy rain in Altadena, we're going to be dealing with the risk of mudslides and all kinds of debris coming into towns."
In this Jan. 10, 2018, file photo provided by Santa Barbara County Fire Department, Kerry Mann navigates the large boulders and mudflow that destroyed the home of her friend in Montecito, Calif. (Mike Eliason/Santa Barbara County Fire Department via AP, File)
One of the most devastating debris flows in recent history occurred on Jan. 9, 2018, when heavy rain soaked the burn scar left by the Thomas Fire, which had torched approximately 440 square miles in Santa Barbara and Ventura counties just weeks earlier.
A torrent of mud, rocks and water surged down the mountainside and through Montecito, California, a town outside of the Thomas Fire burn scar. This catastrophic event obliterated hundreds of homes and tragically claimed 21 lives.
When there is the risk of flooding, debris flows or mudslides, experts recommend following these tips.
•Take action and prepare your property for potential flooding and debris flow. This includes placing sandbags and reinforcing doors and windows.
•Monitor the weather and listen to advice from local officials.
•Have an evacuation plan in place and swiftly follow the directions from emergency responders if an evacuation order is issued.
