The parade of atmospheric rivers that pounded California for three weeks finally faded, enabling the state to begin lengthy repairs to roads and levees as the White House announced President Joe Biden planned to survey the damage.

The nine consecutive rainstorms that inundated California in succession since 26 December killed at least 20 people while tens of thousands remained under evacuation orders as of last night, Governor Gavin Newsom said in an executive order that reinforced the state's response to storm damage.

"The last of the heavier rain in California is slowly fading. After midnight it shouldn't be heavy anymore," said meteorologist David Roth of the National Weather Service's Weather Prediction Center.

Mr Biden will travel to areas of the central coast on Thursday to meet first responders, visit affected towns, and "assess what additional federal support is needed," the White House said.

The president had already issued an emergency declaration on 8 January to free up federal aid and then on Saturday authorised disaster assistance for Merced, Sacramento and Santa Cruz counties.

A damaged lifeguard tower on the Seacliff peer after storms in Aptos

Among the more dramatic images of storm damage were those of Highway 1, the scenic coastal highway near Big Sur, which was closed at several points due to mudslides and falling boulders strewn across the road.

While damaging, the storms also helped mitigate a historic drought, as much of the state has already received half or more its average annual rainfall.

But with more than two months to go in the rainy season, officials are urging Californians to continue conserving water.

The US Drought Monitor still shows almost the entire state under moderate or severe drought conditions.

Reservoir levels were still below average for this time of year, officials said.

A home damaged by a mud slide along Faircliff Street in Hayward

Moreover, the atmospheric rivers largely failed to reach the Colorado River basin, a critical source of southern California's water.

"If you rely on the Colorado River basin as a part of your water supply, then there will be continuing drought problems due to the extreme drought in that part of the world," Michael Anderson, California's state climatologist, told reporters.

The Colorado's two major reservoirs, Lake Mead and Lake Powell, were at 28.5% and 22.6% of capacity, respectively, and still below levels from this time a year ago according

The ninth consecutive atmospheric river fizzled out yesterday, its remnants soaking the southernmost part of the state, Arizona and northern Mexico, Mr Roth said.

Lola Weiselman,7, and her brother Nathan, 9, play in the flooded Kenneth Hahn Park Playground in LA

The storms are akin to rivers in the sky that carry moisture from the Earth's tropics to higher latitudes, dumping massive amounts of rain.

Another storm was coming that could bring moderate rain today and tomorrow.

The US National Weather Service said it lacked the volume to be classified as an atmospheric river, while the state Department of Water Resources said it may briefly qualify as one.

California can otherwise expect dry conditions for the remainder of January, state officials said.