Los Angeles Fire Chief Kristin Crowley said on Tuesday that crews had responded more than 400 mudslides and that five buildings had been deemed uninhabitable since an atmospheric river-fuelled storm moved into the region over the weekend.
Despite the record-setting rain that has drenched the city and caused widespread flooding, there have been no storm-related deaths reported in Los Angeles, Mayor Karen Bass said at a news conference.
The storm continued to pose new hazards on Tuesday, with the National Weather Service issuing a rare tornado warning for inland parts of San Diego County.
The rain began to ease in some area on Tuesday after bombarding Los Angeles with nearly half of its seasonal rainfall in just two days.
Although the rain was tapering off, forecasters warned of the ongoing threat of potentially deadly landslides.
“Angelenos should know that even though the rain may ease up a bit today, this storm continues. And that means we still need Angelenos to take precautions and to stay informed during this time,” the mayor said.
Most of Southern California remained under flood watches, and the weather service warned people to remain on high alert, as swollen and fast-moving creeks and rivers increase the risks of drowning and the need for swift-water rescues.
“This has truly been a historic storm for Los Angeles,” Ariel Cohen, a meteorologist at the National Weather Service’s Los Angeles-area bureau told reporters, noting that the city just recorded its third-wettest two-day stretch since recordkeeping began in the 1870s.
The storm plowed through Northern California over the weekend, killing three people who were crushed by falling trees before moving south and lingering. It was the second storm fuelled by an atmospheric river – a weather pattern made from plumes of moisture that can produce torrential amounts of rain – to hit the state in a matter of days.
On Monday, the storm pounded Los Angeles with rain, sending mud and boulders down hillsides dotted with multimillion-dollar homes while people living in homeless encampments in many parts of the city scrambled for safety.
Near the Hollywood Hills, floodwaters carried mud, rocks and household objects downhill through Studio City, city officials said. Sixteen people were evacuated.
“It looks like a river that’s been here for years,” said Keki Mingus, whose neighbours’ homes were damaged. “I’ve never seen anything like it.”
Drake Livingston, who lives in the Beverly Crest neighbourhood, said: “We looked outside and there’s a foot-and-a-half of running water, and it starts seeping through the doors.”
City centre Los Angeles received nearly seven inches (18cm) of rain by Monday night, which was nearly half the yearly average of 14.25 inches (36cm). It was already the third-wettest two-day period since recordkeeping began in 1877, the service said.
The danger had not passed despite the expected dip in the rainfall, the weather service said.
“The ground is extremely saturated — supersaturated,” meteorologist Mr Cohen said at a news conference on Monday.
“It’s not able to hold any additional water before sliding. It’s not going to take much rain for additional landslides, mudslides, rockslides and other debris flows to occur.”
Rainfall amounts on Tuesday “are not going to be quite as heavy as they have been, but still with the ongoing flooding, any additional rain is not welcome,” National Weather Service forecaster Bob Oravec said early on Tuesday.
More showers are possible on Wednesday and Thursday, Mr Oravec said. “So it doesn’t look like it’s going to be totally in the clear probably until Thursday and into Friday.”
In the Los Angeles area, an evacuation order remained in place for some residents of a canyon area that was scarred by a 2022 fire. The area was at increased risk of mud and debris flows because the area was burned bare of brush and trees that could hold it back, authorities said.
Fires contributed to a tragic 2018 mudslide in Montecito that destroyed 130 homes and killed 23 people, making it one of the deadliest in California history.
The Los Angeles Fire Department said that during this latest bout of bad weather, firefighters had dealt with more than 300 mudslides in addition to more than 100 reports of flooding and rescues of motorists stranded in vehicles on inundated roadways.
Shelters added beds for the city’s homeless population of nearly 75,000 people.