Southern California Braces for Much-Needed Rain This Weekend

While aiding firefighting efforts, the rain also poses risks of mudslides, flash flooding, and hazardous runoff.

Southern California is set to receive much-needed rain this weekend, providing potential relief to firefighters who have been battling destructive wildfires across the Los Angeles area for nearly three weeks. However, the expected precipitation also carries significant risks, including mudslides, flash flooding, and toxic runoff.

The National Weather Service forecasts up to 1.5 inches of rain in the San Gabriel Mountains, with most of Los Angeles County expecting around half an inch starting Saturday afternoon and lasting through Monday. The rain is also accompanied by a 10-20% chance of thunderstorms, which could bring brief heavy downpours, small hail, and rainfall rates of up to 0.50 inches per hour.

The rain will likely assist in controlling the wildfires that have scorched tens of thousands of acres in Los Angeles, Ventura, and Riverside counties. As of Thursday, the Palisades Fire, the largest blaze, was 72% contained after igniting on January 7. Southern California has been enduring a prolonged drought, with Los Angeles having not recorded more than a tenth of an inch of rain since early May.

While the rain will help with firefighting efforts, it also brings heightened risks, particularly in areas recently affected by fires. Burned soil is often less stable and lacks the vegetation needed to anchor it, making it more susceptible to erosion. This increases the likelihood of mudslides, capable of carrying boulders and large debris, which can damage structures, block drainage systems, and pose significant threats to human safety, according to the U.S. Geological Survey.

Earlier this month, a landslide in Pacific Palisades damaged a home that had survived the fires, and local officials have expressed concerns that burn scars could be particularly vulnerable during the rainy season.

Though thunderstorms are unlikely, the National Weather Service warns that isolated brief heavy rain could trigger flash flooding and debris flows in burn areas, particularly where the risk of unstable ground remains.

In response, California Governor Gavin Newsom announced that the state is prepared with sandbags, plastic sheeting, and other resources to protect vulnerable areas. “Even before we saw rain on the horizon in Los Angeles, I directed my departments and agencies to act fast to protect neighborhoods from potentially hazardous debris flows,” Newsom said in a statement.

He also emphasized the importance of mitigating the impact of toxic runoff, which can result from the ashes and chemicals released in burned areas. These materials, which can include lead, asbestos, and hazardous chemicals from burned cars and household items, can wash into the ocean and local waterways after heavy rain.

Los Angeles Mayor Karen Bass also took to social media to assure residents that the city is taking aggressive steps to protect against contamination. “Crews are preparing to stem the flow of toxins from burned areas to our water, beaches, and ocean,” Bass wrote, noting efforts to install reinforced barriers and remove debris while diverting stormwater into sewer systems to prevent pollution.