LOS ANGELES — The first significant storm of the season brought snow and downpours to Southern California that doused wildfires and caused some ash and mud to flow across streets in the Los Angeles area on Monday.

More than an inch (2.5 centimeters) of rain fell in many areas, loosening Los Angeles hillsides burned bare by the recent blaze near the Pacific Palisades neighborhood, where crews cleared inundated roadways including the famed Pacific Coast Highway.

In neighboring Malibu, four schools were closed Monday “due to dangerous road conditions,” the Santa Monica-Malibu Unified School District said in a statement.

Clouds were clearing, but flood watches from lingering pockets of rain were still in effect for fire-scarred areas of the Palisades, Altadena and Castaic Lake.

“All these fresh burns are very susceptible to rapid runoff,” said Joe Sirard, a meteorologist for the National Weather Service’s office for Los Angeles.

Related Story: As Schools in LA Reopen, Parents Worry About Harmful Ash From Wildfires

Storm Impacts on Transportation

North of Los Angeles, snowy conditions late Sunday shut down the mountainous Tejon Pass section of Interstate 5, a key north-south artery for the state. It reopened Monday afternoon. The highway rises to more than 4,100 feet (1,250 meters) between LA and the San Joaquin Valley, making it susceptible to storm closures.

Mountains across San Bernardino and Riverside counties were under a winter storm warning Monday and were forecast to get about a foot (0.30 meters) of snow from the storm. Chains were required for some vehicles heading to ski resorts in the Big Bear Lake area northeast of Los Angeles because of icy roads.

Parts of San Diego County received more than an inch of rain, while other areas got less.

Related Story: Dangerous Winds Return to Southern California as New Wildfires Break Out

Wildfire Containment Progress

The rain began Saturday after months of dry and often gusty weather that created dangerous fire conditions.

Los Angeles County crews spent much of last week removing vegetation, shoring up slopes and reinforcing roads in areas devastated by the Palisades and Eaton fires, which reduced entire neighborhoods to rubble and ash after breaking out during powerful winds Jan. 7.

The Palisades Fire, the largest of the blazes that destroyed thousands of homes and killed at least 12 people, reached 94% containment Monday. The Eaton Fire, which broke out near Altadena and has killed at least 17 people, was 98% contained.

The Hughes Fire, which ignited north of Los Angeles last week and caused evacuation orders or warnings for more than 50,000 people, was nearly contained.

Downpours in San Diego County, helped firefighters make significant progress against the smaller Border 2 Fire churning through a remote area of the Otay Mountain Wilderness near the U.S.-Mexico border.

Related Story: Shohei Ohtani Is Donating $500,000 to Help Firefighters and Others Affected by ...

Post-Fire Cleanup and Safety Measures

Los Angeles city and county officials last week expedited cleanup efforts and other measures aimed at mitigating the environmental impacts of fire-related pollutants, and a White House statement on Friday said President Donald Trump has directed federal officials to help local authorities. Within five days of the order, the Federal Emergency Management Agency and other departments “shall develop and execute a plan to expedite the bulk removal of contaminated and general debris,” the statement said.

Officials cautioned that ash in recent burn zones was a toxic mix of incinerated cars, electronics, batteries, building materials, paints, furniture and other household items. It contains pesticides, asbestos, plastics and lead. Residents were urged to wear protective gear while cleaning up.

Concerns about post-fire debris flows have been especially high since 2018, when the town of Montecito, up the coast from Los Angeles, was ravaged by mudslides after a downpour hit mountain slopes charred by a huge wildfire. Hundreds of homes were damaged and 23 people died.

The rain ended a near-record streak of dry weather for Southern California. Most of Southern California is currently in “extreme drought” or “severe drought,” according to the U.S. Drought Monitor.