The thousand-mile coast of California is covered in warnings, watches and advisories for rain, flooding and high surf as another El Nino storm moves in from the Pacific.
The system will pack colder temperatures, stronger winds and heavier rainfall than the two previous storms that have battered the state since the weekend.
Motorists in mountain areas are warned that blizzard conditions are possible above 4,000ft - including several inches of snow and wind gusts up to 60mph.
Flash flooding and flows of mud and debris are a worry in foothill neighbourhoods beneath areas left barren by last year's wildfires.
The National Weather Service says 1.42 inches of rain fell on Tuesday at Los Angeles International Airport, beating the 1979 record for the date by a tenth of an inch.
Meanwhile, a small earthquake gave an early morning wake-up call to the inland region of southern California.
The US Geological Survey said the magnitude-4.5 jolt on Wednesday morning and was centred two miles north of Banning, about 85 miles east of Los Angeles.
The Riverside County Fire Department received no reports of problems from the quake.
USGS seismologist Lucy Jones said the area has a history of many quakes in the magnitude-4 range.
Banning is a small city along Interstate 10 in the San Gorgonio Pass between the San Bernardino and San Jacinto mountain ranges.
The latest El Nino storm hit at the height of the San Francisco commute, causing car crashes, toppling trees and flooding streets and streams around most of the region.
The California Highway Patrol estimated there were nearly two dozen weather-related crashes on Wednesday during the morning drive.
The National Weather Service has issued a flash-flood watch for nearly the entire San Francisco Bay Area.