Officials warned the storm threatens flooding and travel delays across much of the state through Christmas, AFP reported.
The National Weather Service said a “strong atmospheric river brings heavy rain, snow, and wind to California through Friday.”
It urged people in northern, central and southern California to “exercise extreme caution.”
National Weather Service meteorologist Ariel Cohen advised people to reconsider Christmas travel plans.
The storm is driven by an atmospheric river known as “the Pineapple Express.”
It moves heavy moisture from Hawaii to dump rain and snow on the West Coast for several days.
Cohen said significant flooding is likely from late Wednesday through Friday.
Rockslides and mudslides are expected, especially in high terrain and canyon roadways.
Some Southern California communities could see up to 12 inches of rainfall.
Recent burn areas remain highly susceptible to mud and debris flows.
This includes areas impacted by major January wildfires in Los Angeles.
LA county officials confirmed the heightened risk in a statement.
More than 200 homes were placed under evacuation orders on Tuesday.
Flood watches were in effect for much of Los Angeles County and other areas.
In the Sierra Nevada, more than a foot of snow had already fallen this week.
Up to five feet of snow is forecast before the storm ends.
The storm is also expected to bring wind gusts of up to 55 mph.
Weather officials warned of widespread downed trees and power lines.
They stated that “lives and property are in great danger.”