Crews work at removing fallen trees blocking Highway 101 in Humboldt County near Trinidad, Calif., on Wednesday. Caltrans District 1 via AP

SAN FRANCISCO — Officials in California ordered evacuations in a high-risk coastal area where mudslides killed 23 people in 2018 as a huge storm barreled into the state on Wednesday, bringing high winds and rain that threatened to knock out power and flood roadways.

California Gov. Gavin Newsom declared a state of emergency to allow for a quick response and to aid in cleanup from another powerful storm that hit just days earlier. Dozens of flights out of San Francisco were canceled, and schools in one of the city’s suburbs preemptively canceled Thursday classes. Officials warned people throughout Northern California to stay off the roads.

“We anticipate that this may be one of the most challenging and impactful series of storms to touch down in California in the last five years,” said Nancy Ward, the new director of the California Governor’s Office of Emergency Services.

The storm, which brought howling winds to Northern California on Wednesday evening, is one of three so-called atmospheric river storms in the last week to reach the drought-stricken state. In Southern California, the storm was expected to peak in intensity overnight, with Santa Barbara and Ventura counties likely to see the most rain, forecasters said.

The first evacuations were ordered for those living in areas burned by three recent wildfires in Santa Barbara County, where heavy rain forecast for overnight could cause widespread flooding and unleash debris flows. County officials did not have a firm number for how many people were under evacuation orders, but Susan Klein-Rothschild, a spokesperson in the county’s emergency operations center, estimated it was in the hundreds.

Among the towns ordered to evacuate was Montecito, where five years ago huge boulders, mud and debris swept down mountains through the town to the shoreline, killing 23 people and destroying more than 100 homes. The town is home to many celebrities, including Oprah Winfrey and Prince Harry and his wife, Meghan.

“What we’re talking about here is a lot of water coming off the top of the hills, coming down into the creeks and streams and as it comes down, it gains momentum and that’s what the initial danger is,” Montecito Fire Department Chief Kevin Taylor said.

Elsewhere, a 45-mile stretch of the coastal Highway 1 that runs through Big Sur was closed Wednesday evening in anticipation of flooding and rock falls. Further north, a 25-mile stretch of Highway 101 was closed due to several downed trees.

Officials asked drivers to stay off the roads unless absolutely necessary — and to stay informed by signing up for updates from emergency officials about downed trees and power lines, and flooding.

A man loads the back of his car with sandbags on Wednesday in Pacifica, Calif. Haven Daley/Associated Press

The storm was forecast to drop up to 10 inches of rain on an area where the hills have already been saturated over the past month.

The storms won’t be enough to officially end the state’s ongoing drought, now entering its fourth year. The U.S. Drought Monitor showed that most of California is in severe to extreme drought. Since the state’s major reservoirs are low, they have plenty of room to fill with more water from the storm, officials said.

Still, trees are already stressed from years of limited rain. Now that the grounds are suddenly saturated and winds are heavy, trees are more likely to fall. That could cause widespread power outages or create flood hazards, said Karla Nemeth, director of the state’s Department of Water Resources.

“We are in the middle of a flood emergency and also in the middle of a drought emergency,” she said during an emergency briefing.

The storm comes days after a New Year’s Eve downpour led to the evacuations of people in rural Northern California communities and the rescue of several motorists from flooded roads. A few levees south of Sacramento were damaged.

In the San Francisco Bay Area, 8,500 sandbags distributed by officials weren’t enough to reach demand Wednesday as forecasters warned of imminent flooding.

Robert O’Neill, an insurance broker who lives and works just south of San Francisco, said he lined up to get sandbags for his garage and for a co-worker’s home to prepare for the storm.

As president of Town & Country Insurance Services, he gave employees the option of working from home Wednesday, which many did, he said. He planned to leave the office early and head home where he has water and food and go-bags packed with clothes, medicine, electronic chargers and important papers.

“We’re in a big city, so we wouldn’t be too stranded too long, but you never know,” he said.

Storms were taking a toll elsewhere in the U.S. as well. In the Midwest, ice and heavy snow this week closed down schools in Minnesota and western Wisconsin and caused a jet to go off an icy taxiway after landing in a snowstorm in Minneapolis. No passengers were injured, Delta airlines said.

To the south, a possible tornado damaged homes, downed trees and flipped a vehicle on its side in Montgomery, Alabama, early Wednesday.

In Illinois, staff from the National Weather Service’s Chicago office planned to survey storm damage on Wednesday following at least six tornados, the largest number of rare January tornadoes recorded in the state since 1989.

Associated Press writers Janie Har in San Francisco, Sophie Austin in Sacramento, California, Steve Karnowski in Minneapolis and Rick Callahan in Indianapolis contributed to this report.