A monster United States winter storm has pounded the Northern Plains and Upper Midwest, killing a firefighter, knocking out power to almost one million people and cancelling or delaying thousands of flights.

A broad swath of the northern US from Washington state to New England remained under winter weather advisories with another 46cm of snow, winds of up to 80km/h and wind chills equivalent to minus 40 degrees Celsius possible throughout the day, the National Weather Service said.

A volunteer firefighter was killed in suburban Grand Rapids, Michigan, after coming in contact with a live power line knocked down by ice, local officials said on Twitter.

More than 900,000 homes and businesses were without power in Illinois, Indiana, Michigan, New York and Wisconsin on Thursday morning, according to Poweroutage.us.

At least 2000 flights were cancelled and another 15,000 were delayed due to the heavy weather, according to flight-tracking website Flightware.com.

Many roads were left impassable or treacherous to drivers.

"Travel on the roads can be dangerous with just a trace of ice but we're seeing ice caking from a quarter to half inch (6mm to 1.3cm)," said Richard Bann, of the weather service's Weather Prediction Center in College Park, Maryland.

"That can be practically impossible."

Snow fell at a rate of 2.5 to 5cm an hour in Minneapolis, home to about 2.9 million people.

New accumulations added to the 20cm of snow already dumped by the storm.

Video footage and photographs on social media showed cars stuck on roadways, while streets and walkways were covered in drifting snow.

The Minneapolis school system was holding classes remotely for more than 29,000 pupils for the rest of the week.

Dozens of school districts also cancelled classes in North and South Dakota, Colorado, Michigan and Wyoming

In Ann Arbor, Michigan, home of the University of Michigan, almost 20,000 homes and businesses lost power.

A separate storm spawned unusual weather in California, where much of the state was under high wind and winter storm warnings.

Rare snow flurries were reported in San Francisco while blizzard conditions were expected in high elevations, even in the typically balmy Los Angeles area.

By Saturday, up to 2.4 metres of snow could accumulate on Mount Baldy, about 72km east of Los Angeles in the San Gabriel Mountains.

At the same time, parts of the Ohio Valley and the South could see near-record-breaking high temperatures lingering into the weekend.

Weather forecasters predicted temperatures to hit 31C in Jacksonville, Florida on Sunday.