This blog post summarizes a rare October storm that drenched Southern California, producing several inches of rain, flash floods, and mudslides in burn-scarred areas. I review the storm’s impacts across Los Angeles and surrounding counties. I also explain why post-fire landscapes are particularly vulnerable to runoff and debris flows. Practical safety and preparedness guidance is offered based on three decades of experience in emergency response and wildfire recovery.
What happened during the October storm
The storm delivered intense, localized rainfall across Southern California, with as much as 1.5 inches recorded in parts of Los Angeles. More than 5 inches fell in the higher elevations of the San Gabriel Mountains.
The National Weather Service issued multiple flash flood warnings as rain-swollen rivers and unstable slopes triggered evacuations, rescues, and travel disruptions. Power outages affected more than 21,000 customers.
Emergency teams responded to water rescues, debris flows, and rockslides over a compact area.
Local impacts: Los Angeles, Pacific Palisades, Mandeville Canyon and Sierra Madre
Los Angeles saw dramatic instances of urban and hillside flooding. Firefighters rescued two people and two dogs from the Los Angeles River.
Roughly 115 homes in Pacific Palisades and Mandeville Canyon were temporarily evacuated as mud and runoff threatened neighborhoods below burn scars. In Sierra Madre, debris flows trapped vehicles and damaged homes.
In one striking image a Los Angeles Fire Department vehicle was swept into the ocean. The storm also produced unexpected hazards such as rockslides and even tornado warnings in the region.
The rapid onset of debris flows and trapped motorists underlines the speed at which conditions can deteriorate after wildfire.
Why burn scars magnify flood and debris-flow risk
As an emergency manager who has studied post-fire hydrology for 30 years, I can confirm that soils altered by wildfire behave very differently in storms. Fire can render soil hydrophobic—essentially creating an impermeable layer that prevents infiltration and increases surface runoff.
The result is a higher likelihood of rapid, concentrated flows that mobilize sediment, ash, and boulders. These fast-moving debris flows follow drainage channels into communities below.
Vegetation that formerly slowed and absorbed rainfall is gone. Slopes are left exposed and unstable.
Practical advice: preparedness and response
Residents in fire-affected and foothill communities should be particularly vigilant during rainy seasons.
Based on experience, I recommend the following actions:
The October storm also fits into a broader pattern of extreme weather across the United States this week.
Floods in Colorado, severe wind damage in Arizona, and deadly coastal flooding in Alaska followed Typhoon Halong.
A Coast Guard rescue off Cape Cod, saving a man adrift in rough seas, capped a week of nationwide extremes.
Here is the source article for this story: Rare October storm in Southern California prompts evacuations and causes freeway accidents