In California, where some areas have seen as much rain in three weeks as they normally do in an entire year, the last in a series of deadly storms is expected to leave the state on Monday.

Since late December, Californians have been pummeled by historic levels of rain and snow that have swollen rivers, flooded roads and homes, forced evacuations, and knocked out power to millions.

"The rain will finally start to end for California by Monday night, ushering in what looks to be a much drier period of weather after weeks of relentless heavy rain," the National Weather Service wrote in its forecast for Monday.

At least 19 people have died in connection with the storms. In San Luis Obispo County, officials on Sunday were still searching for a 5-year-old boy who was swept away by floodwaters near San Miguel last week; the persistent rain had pushed water levels in nearby waterways so high that rescuers spent days unable to search.

Pacific Gas & Electric, the state's largest electricity provider, said that more than 2.6 million customers had lost power at some point since the storms began late last month. As of mid-day Monday, about 42,000 customers were without power, according to poweroutage.us.

"It's been the most impactful storm series that we've seen since 1995 when our outage records began," said PG&E meteorologist Scott Strenfel in a Sunday update from the utility company. "This looks to be the last storm in this long series, and hopefully we'll get some blue skies after this."

Since December, a series of "atmospheric rivers" have brought record storms to California. The meteorological phenomenon swept moisture from the tropics up to the higher latitudes of the U.S. West Coast, sending storm after storm sailing into California.

Almost the entire state had received 400% to 600% of its typical average rainfall since Christmas, according to the NWS.

At San Francisco International Airport, 20.3 inches of rain had fallen since the start of the "water year," which runs from Oct. 1 to Sept. 30. That has already topped the annual average of 19.64 inches, with more than 8 months left to go.

On Saturday, President Joe Biden approved the state's request for a federal disaster declaration, making federal funding available to Merced, Sacramento and Santa Cruz counties, the three counties most affected by the storms.

The relentless rainfall has saturated the ground, leading to knock-on problems with mudslides, sinkholes and downed trees that have damaged roads and homes.

More rain had come in overnight as the storm passed through on Monday, dropping up to 2 inches in some places along the Sierra Nevada mountain range and in Southern California's Transverse Ranges.

At least 16 California counties were under a flood warning or flood advisory on Monday, most of them concentrated around the Bay Area and areas east, including Sacramento and the foothills of the Sierra Nevada.

Higher elevations of the Sierra were expected to get another 1 to 3 feet of snow, complicating travel on mountain roads. Officials closed U.S. Highway 50 just west of Lake Tahoe, citing heavy snow and avalanche control, while snow and ice on Interstate 80 prompted officials to put in place a temporary speed limit of 30 miles per hour.

Throughout California, waterways, drainage ditches and low-lying areas all continued to be prone to flooding on Monday, forecasters warned, including in San Joaquin County, where a rescue team evacuated 175 residents from a flooded mobile home park on Sunday.

And much of the state's coastline — from Point Reyes, 30 miles north of San Francisco, through the central coast to the beaches of Los Angeles — had coastal flood advisories active into Monday, with the weather service warning of waves 10 feet tall or higher and dangerous rip currents.

But by midday Monday, the NWS had begun to cancel those alerts as the storm moved eastward.

One small, weak storm is expected to move quickly across the state late Wednesday.

"After that, we're looking for a period of dry weather for much of the state, finally, as we head into late week and pretty much through the weekend," said David Lawrence, an NWS meteorologist. [Copyright 2023 NPR]