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Forecast for heaviest period of rain lasts until Monday afternoon. What we know about risks for mudslides
After the Thomas Fire, heavy rains triggered tremendous mud and debris flows in Montecito in early 2018. Rains following fires always raise concerns.
(
Al Seib
/
Los Angeles Times via Getty Images
)
With the arrival of much-needed rain finally, debris flows are a real concern below steep, recently burned areas. Just how much water, rock, mud and other debris can flow will depend on how much rain falls in a short period.
Where things stand
Rain is expected to stick around from Saturday through Monday, though the period of greatest risk will be between 4 p.m. Sunday and 4 p.m. Monday. That's when the heaviest precipitation is expected to fall, according to the National Weather Service.
While 0.25 inches an hour is likely across the broader region, isolated thunderstorms could drop more than 0.5 inches an hour, exceeding the threshold of concern for debris flows. Anticipate problems if rainfall rates exceed a quarter-inch in 15 minutes, especially in mountainous areas.
FLOOD WATCH is in effect for 4pm Sun to 4pm Mon. Here are the key details. While damaging debris flows are not the most likely outcome, there is still a lot of uncertainty with this storm. The threat is high enough to prepare for the worst-case scenario. #PalisadesFire #EatonFire pic.twitter.com/bbBGMJX90Y
— NWS Los Angeles (@NWSLosAngeles) January 25, 2025
The NWS will issue additional flood watches as needed.
What we know about the risks
"I'm most worried about the Eaton Fire," said Jason Kean, research hydrologist with the U.S. Geological Survey.
That's because the steepness of the San Gabriel Mountains and the deep drainages that run throughout can capture tons of debris, funneling mud, plants and rocks toward communities below. There's a long history of mudslides in the area, which is why a network of debris basins was built.
While the overall risk should be quite low for this rain event, that doesn't mean we won't see isolated problems.
“The worst would be a debris flow that’s several feet deep, that closes roads in the area, isolates people in their homes and brings mud into homes,” said Ryan Kittell, meteorologist with the NWS.
If you live downhill from one of the burned areas and feel especially concerned, consider leaving ahead of the storm. If you choose not to leave, it would be a good idea to stock up with a few days' worth of food and water in case roads are blocked.
Post-fire debris flow risk is highest right after a wildfire, but lasts anywhere from three to five years after a blaze, depending on how much rain an area gets and how long it takes for plants to repopulate hillsides.
Not every fire gets a post-fire debris flow risk assessment. So far, the USGS has only received requests to perform debris flow modeling for the Eaton, Palisades and Hurst fires, according to Kean.
Palisades Fire
Palisades Fire perimeter and evacuation orders
(
CalFire
)
- Acreage: 23,448 acres | Containment: 77%
- Structures damaged or destroyed: 5,000 estimated destroyed, about 700 damaged | Deaths: 11
- CalFire incident page
The Palisades Fire decimated significant sections of Pacific Palisades and Malibu.
Mudslide risk assessment:
Darker areas on the map are assessed as being most likely to see debris flow.
(
U.S. Geological Survey
)
Eaton Fire
Eaton Fire perimeter.
(
CalFire
)
- Acreage: 14,021 | Containment: 95%
- Structures damaged or destroyed: About 9,400 destroyed, more than 1,000 damaged | Deaths: 17
- CalFire incident page
The Eaton Fire devastated whole neighborhoods of Altadena and forced mass evacuations from parts of Altadena, Pasadena, Sierra Madre and Glendale.
Mudslide risk assessment:
Darker areas are assessed as being more likely to see debris flows.
(
Courtesy USGS
)
Hughes Fire
Hughes Fire perimeter as of Friday, Jan. 24.
(
CalFire
)
- Acreage: 10,396 | Containment: 56%
- Structures damaged or destroyed: None
- CalFire incident page
The Hughes Fire prompted the temporary shutdown of the 5 Freeway, evacuation orders and the shut down of many schools.
Mudslide risk assessment: The risk is still being assessed by the U.S. Geological Survey.
Hurst Fire
The Hurst Fire burn zone.
(
CalFire
)
- Acreage: 799 acres | Containment: 100%
- Structures damaged or destroyed: None
- CalFire incident page
The Hurst Fire started above Olive View Medical Center and spread toward the 210 Freeway in Sylmar.
Mudslide risk assessment:
Darker areas are assessed as being more likely to see debris flows.
(
U.S. Geological Survey
)
Kenneth Fire
The area burned by the Kenneth Fire.
(
CalFire
)
- Acreage: 1,052 acres | Containment: 100%
- Structures damaged or destroyed: None
- CalFire incident page
The Kenneth Fire that broke out along the western edge of the San Fernando Valley and was fully contained relatively quickly. The fire started in the Upper Las Virgenes Canyon Open Space Preserve and pushed toward dense developments in the cities of Calabasas and Agoura.
Mudslide risk assessment: A USGS risk assessment wasn't performed for this fire.
Sunset Fire
Area burned by the Sunset Fire.
(
CalFire
)
- Acreage: 61 acres | Containment: 100%
- Structures damaged or destroyed: None
- CalFire incident page
The Sunset Fire forced evacuations of densely populated areas in the Hollywood Hills before being contained.
Mudslide risk assessment: A USGS risk assessment wasn't performed for this fire.
Other recent fires
Franklin Fire
- Acreage: 4,037 acres | Containment: 100%
- Structures damaged or destroyed: 28 damaged, 20 destroyed
- CalFire incident page
The Franklin Fire sparked on Dec. 18 and was active for nine days.
Mudslide risk assessment:
Darker areas have been assessed as more likely to see debris flow.
(
U.S. Geological Survey
)
Auto Fire
- Acreage: 61 acres | Containment: 100%
- Structures damaged or destroyed: None
- CalFire incident page
This fire burned in a riverbed area in Ventura and was quickly contained.
Mudslide risk assessment: A USGS risk assessment wasn't performed for this fire.
Lidia Fire
- Acreage: 395 acres | Containment: 100%
- Structures damaged or destroyed: None
- CalFire incident page
This fire burned in a remote area north of Soledad Canyon Road in L.A. County.
Mudslide risk assessment: A USGS risk assessment wasn't performed for this fire.
Sepulveda Fire
- Acreage: 30 acres | Containment: 100%
- Structures damaged or destroyed: None
- CalFire incident page
The Woodley Fire was reported near North Woodley Avenue and the Sepulveda Basin. In the early hours of the fire, officials warned that it posed "a threat of crossing Burbank Boulevard."
Mudslide risk assessment: A USGS risk assessment wasn't performed for this fire.
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Do you have a question about the wildfires or fire recovery?
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Fire resources and tips
Check out LAist's wildfire recovery guide
If you have to evacuate:
- Why fire officials don't want you to stay and defend your home
- How to get packed up
- How to leave your house
- What evacuation terms mean and how to sign up for alerts
Navigating fire conditions:
- How to drive in high winds and fire danger
- How to prep for power outages
- How to navigate poor air quality
How to help yourself and others:
- Resources for fire victims, evacuees and first responders
- If you want to help fire victims, resist the urge to volunteer
- How to help find lost pets
How to start the recovery process:
- What to do — and not do — when you get home after a wildfire
- How to make an insurance claim
- How to safely clean up wildfire ash
What to do for your kids:
- How to talk to children about wildfires and losing a home
- What parents should know about wildfire air quality
Prepare for the next disaster:
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