Henry Laguna walks around his property after a mudslide caused by heavy rains damaged his house in La Canada Flintridge, a neighbourhood of Los Angeles, on Monday. (Hector Mata/Associated Press)

Some Southern California residents packed their cars and fled Tuesday over fears of mudslides as evacuation orders took hold and a new winter storm approached.

Officials issued evacuation orders for 541 homes on the hillsides of La Canada Flintridge, La Crescenta, Acton and two canyons north of Los Angeles. Los Angeles County sheriff's deputies went door to door, urging people to leave. Those who refused signed waivers stating that they were aware of the risk.

Sheriff's deputies also asked residents to move their vehicles and trash cans away from the streets, where water and rocks roared through, smashing cars and concrete barriers together on Saturday morning.

Many people heeded the warning, lugging clothing and backpacks to cars that rolled down roads already crusted with the remains of a weekend mudslide that damaged 43 homes.

Vachik Salemi told KTLA-TV that he was tired of leaving and would not evacuate. He said he has been evacuated from the area six times.

"You can see nothing happened to our house," he said. "By staying, maybe … we can help other people that are staying behind."

Weather forecasters issued a flash flood watch for Tuesday afternoon through late Tuesday night for neighbourhoods below steep slopes that were scorched by the fires last summer.

The National Weather Service said there was a chance of thunderstorms that could dump more than 50 millimetres of rain in the foothills of the San Gabriel Mountains, where debris basins overflowed and damaged homes over the weekend. The basins are designed to keep mud and boulders away from homes near the burn areas.

About 300 trucks are being used to clear the debris channels.

"It takes weeks to clean the debris basins out entirely. We've been working around the clock since Saturday, load after load after load," said Department of Public Works spokesman Bob Spencer.

"Hopefully this storm will be kinder to us."

The showers could put more pressure on the basins. Engineers have prioritized six of the 28 basins in the burn area, based on their size, current capacity and proximity to at-risk neighborhoods, Spencer said.