California storms death toll climbs to 20

The parade of atmospheric rivers that have doused California for three weeks is finally fading, enabling some evacuees to return home and the state to concentrate on repairing washed-out roads, breached levees and downed power lines.

Nine consecutive rainstorms that pounded California in succession since December 26 have killed at least 20 people while tens of thousands remained under evacuation orders as of Monday, 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," National Weather Service meteorologist David Roth said.

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

With more than two months to go in the rainy season, officials are urging Californians to continue conserving water as the US Drought Monitor still puts almost the entire state under moderate or severe drought conditions.

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

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," California's state climatologist Michael Anderson told reporters.

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

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 impending storm could bring moderate rain on Tuesday and Wednesday.

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 might briefly qualify as one.

Otherwise, California can expect dry conditions for the rest of January, state officials said.

Even so, forecasters warned mud and rockslides are possible in canyons and steep hills as the ground is saturated after three weeks of rain and snow.

Some rivers had yet to crest, posing flood threats.

Local and state emergency declarations remained in effect in many counties.