The rainfall arrives about two months after January wildfires in Southern California, including the Palisades and Eaton fires in Los Angeles County. The fires stripped brush from hillsides, leaving them more vulnerable to mud and debris flows as rainfall rates increase.

The first storm, said Scott Kleebauer, a meteorologist at the National Oceanic and Atmospheric Administration's weather prediction center, "is kind of meandering off the Southern California coast, and will slowly be pushing inland by later this afternoon and this evening.

Southern California welcomed a surge of moisture that forecasters say could be the first in a series of early March storms, including a potential atmospheric river.