A pedestrian navigates a snow-covered sidewalk in Iowa City, Iowa, on Wednesday. AFP

Swaths of the United States braced for more snow and punishingly low temperatures on Wednesday as millions in the east dug out from a previous round of severe winter weather that left at least five people dead.

The latest storm, already bringing precipitation to the West, was expected to tear across the country this week, bringing an Arctic blast to northern regions and prompting weather advisories or warnings in dozens of states from California to Maine.

A pedestrian makes their way along 2nd Street SE as snow falls in Cedar Rapids, Iowa, on Tuesday. AP

Tens of millions of Americans were under the threat of menacing weather on Wednesday as a powerful winter storm loomed across the East Coast after leaving in its wake power outages, grounded flights and destruction.

At least five storm-related deaths have been recorded, including an 81-year-old Alabama woman whose mobile home was reportedly struck by a tornado.

FLIGHTS CANCELLED OR DELAYED

The weather was already having a heavy impact on flights, with more than 659 cancelled and 1,300 delayed in the United States early Wednesday, monitoring website FlightAware.com reported.

A school bus is driven along a snow-covered street  in Wheeling. AP

Scientists say that as humanity continues to warm the planet by burning fossil fuels, weather patterns will become more unpredictable.

More than 90 million people from eastern Ohio and Kentucky and up through the Mid-Atlantic and into the Northeast were under high wind and flooding advisories on Wednesday, the National Weather Service (NWS) said.

People sled on the campus of the University of Iowa in Iowa City, Iowa, on Tuesday. AFP

Major cities such as New York, Philadelphia and Boston were expected to see flood-inducing rains taper off in the morning and potentially damaging gusts of more than 80km per hour that could take down trees and powerlines during the day, the NWS said.

"While much of the rain has now exited the area, we are still lingering with the effects. In particular, many rivers and streams continue to rise into moderate to major flood stages with flood warnings in place," the NWS in New York City said on X.

500,000 WITHOUT POWER

Some 500,000 homes and businesses from Florida north to Maine were without power early on Wednesday, Poweroutage.us reported.

The storm was already responsible for at least three deaths in Alabama, North Carolina and Georgia, where high winds and several tornadoes ripped through parts of the South, according to authorities and local media reports. Two motorists were also killed in Wisconsin and Michigan, where heavy snow fell across the region, causing treacherous driving conditions, local media reported.

A separate winter storm was expected to continue during the day in the Pacific Northwest, where many communities in higher elevations were expected to get

The extreme weather follows a record number of "billion-dollar" disasters in the US last year. "This snow will cling to trees and power lines, which when combined with gusty winds potentially exceeding 55 mph, could result in power outages," the NWS said.

In the Pacific northwest, a separate storm system is producing blizzard conditions that will continue into Wednesday, producing several feet of snow at higher elevations in the Cascade mountains in Washington and Oregon, the NWS said.

That storm system will strengthen as it roars over the Rockies and onto the central plains by Thursday.

Agencies