US President Joe Biden will travel to flood-hit areas of California on Thursday, the White House said, as the country's most populous state cleans up from a devastating and lethal series of storms.

Biden will tour storm-devastated communities, "survey recovery efforts, and assess what additional federal support is needed," the White House said late Monday in a statement.

Nine successive storms have rolled in from the Pacific Ocean, slamming California and other western regions in a three-week period of extreme weather that has cost 19 lives.

Biden declared a major disaster in California over the weekend, allowing the federal government to expedite aid, including help with temporary housing and repairs.

Damage estimates from the series of storms already top $1 billion, making for the most costly disaster so far of 2023.

Even as scattered sunny skies were predicted for Tuesday, it won't be much of a respite for relief workers in California hustling to clear landslides, shovel mud from roads and remove fallen trees.

Some 23,800 homes in the state remained without power late Monday, according to poweroutage.us.

Sodden cities in northern California reported staggering accumulated quantities of rain. A report from the National Weather Service (NWS) for the Bay Area said more than 18 inches (45 cm) of rain have fallen on San Francisco since December 26.

"It's the wettest 22-day period since January 14, 1862," the NWS office said in a tweet.

In the Central Valley, the fertile region that produces 40 percent of US fruits, Modesto reported more than an inch of rain Monday, beating an old record set in 1950, and Stockton had 1.2 inches of rain, surpassing a record set there in 1973, the NWS office in Sacramento tweeted.

The relentless winter storms have largely passed over the state and are now hitting Rocky Mountain and Great Plains states.

An NWS short-range forecast said "heavy snowfall" was expected in mountainous parts of Colorado, New Mexico and Utah "through Tuesday before advancing east into the Central Plains on Wednesday."

While California is seeing some relief, a new storm system looms off Washington state to the north.

"There will be a new storm system arriving across the Pacific Northwest by Tuesday night and advancing inland by Wednesday," the NWS forecast said.

"This will bring a new surge of Pacific moisture and a round of heavy rainfall for especially the coastal ranges and the foothills of the Cascades," it added.