An atmospheric river is bringing historic rainfall to Southern California.
A second storm within one week is pummeling California with heavy rain and life-threatening flooding.
Gov. Gavin Newsom has issued a state of emergency for counties including Los Angeles, Santa Barbara and Ventura, where floodwaters and mudslides have swept through roadways.
More than 516,000 customers in California are waking up without power Monday morning as a powerful rainstorm slams the state.
Flash flood warnings and flood advisories are in effect for parts of Los Angeles and Ventura counties.
Los Angeles recorded more than 4 inches of rain on Sunday, beating the city's daily record of 2.55 inches set in 1927.
The relentless rainfall and life-threatening flooding are ongoing across the Los Angeles area on Monday morning and will continue throughout the day.
A flash flood warning is in effect from Malibu to Beverly Hills to Brentwood to Hollywood to Burbank.
By Tuesday morning, the heaviest rain will be targeting areas east of San Diego.
On Tuesday afternoon, scattered downpours continue throughout California, and by Wednesday, just a few light showers and sprinkles will remain.
The National Weather Service has a flood watch in effect Monday morning for some 40 million residents in California, where more than a month's worth of rain has fallen in the past 24 hours.
There was also a flash flood warning in effect until at least 9 a.m. PT for more than 4 million residents in Southern California, from the Santa Monica Mountains to the Hollywood Hills and Griffith Park, including the areas of Hollywood, Malibu, Beverly Hills, Burbank, Santa Monica, Encino and Brentwood. There were reports of numerous damaging landslides, inundated roadways, submerged vehicles as well as flooded creeks and streams within the region.
Automated rain gauges indicate between 5 and 8 inches of rain have already accumulated in the warning area, with rainfall continuing. An additional 1 to 4 inches of rain was possible there.
-ABC News' Kenton Gewecke and Morgan Winsor
Power is out for hundreds of thousands of electric customers in California amid severe weather.
As of 2:40 a.m. PT on Monday, more than 634,000 customers were without power across the Golden State, according to data collected by PowerOutage.us.
-ABC News’ Morgan Winsor
