A winter storm on the northeastern coast of the United States and floods in the west of the country caused power outages in hundreds of thousands of American homes on Wednesday, and disrupted public services, amid expectations of more rain and snow.

And the specialized “PowerAutage” website confirmed the power outages in about 200,000 homes and businesses in western California, and in a large number of buildings in five states in the northeast, from New York to Boston.

Heavy snowfall and winds knocked down trees on coastal roads, making them impassable, according to local meteorological services.

"Our crews are working tirelessly to get everyone's power back," New Hampshire Emergency and Safety Services said on Facebook, but "it's snowing outside."

Authorities have repeatedly called on residents to be careful, particularly of the risks of injury or heart attacks while shoveling snow.

In Massachusetts, schools continued to be closed Wednesday in many areas, including Berkshire County, where snowfall reached 71 centimeters.

"An additional 7 to 20 centimeters of snow is expected in parts of New York state and the New England region through Wednesday," the National Weather Service said in its latest bulletin on Wednesday morning.

On the other side of the country, the state of California witnessed sporadic floods on Wednesday as a result of heavy rains in the state, the largest in terms of population, which includes 39 million people.

"Atmospheric River" will continue to affect California through Wednesday. The powerful storm is expected to produce heavy snowfall in the mountains and gusty winds from the Sierra into the central and northern Rocky Mountains, the National Weather Service said.

The "atmospheric river" consists of a giant rainforest that transports stored water vapor from the tropics, mostly around Hawaii, and causes very wet winters on the West Coast.

This past weekend, homes and cars were inundated after the Pajaro River flooded, causing a crack in a dam overnight Friday-Saturday and prompting the evacuation of thousands of people south of San Francisco.

Evacuations have also been ordered in Santa Barbara County in the south of the state and in parts of the upscale coastal enclave of Montecito, where Prince Harry and his wife Meghan live.