In view of the ongoing storms in California, US President Joe Biden has declared a state of emergency for the state.
Federal funds can thus be released for temporary accommodation and reconstruction, among other things, as the White House announced late Saturday evening (local time).
There could also be grants for emergency accommodation, home repairs and uninsured property damage, it said.
Since December 27, California has been hit by severe winter storms, flooding, landslides and mudslides.
Severe weather warnings apply to millions of residents, thousands of households are without electricity.
On Saturday, the usually sun-drenched west coast state saw further heavy rain and some snowfall.
So far, at least 19 fatalities have been counted, for example from falling trees or flash floods.
Flooding returned on Sunday night.
Fields and roads were flooded in many places, and power lines were damaged.
Around midnight (local time), around 16,000 households were without electricity, according to the website poweroutage.us.
"We're not done yet," US state governor Gavin Newsom warned on Saturday after visiting those affected.
He warned to remain "vigilant".
The prevailing weather pattern was expected to bring heavy rain, strong winds and snow in the mountains.
According to the National Weather Service (NWS), wet weather from the Pacific is expected to continue on Monday.
The NWS predicted "catastrophic flooding" for the Salina Valley south of San Francisco.
According to a journalist from the AFP news agency, the Salinas River has already burst its banks in many places and flooded fields.
In the mountains, the precipitation led to heavy snowfall.
The authorities warned of the danger of avalanches.
Almost 26 million Californians were still affected by flood warnings on Saturday evening, according to the US weather service NWS.
Tens of thousands of people were called to evacuate their homes.