A wild winter storm continues to envelop much of the United States, bringing blinding blizzards, freezing rain, flooding and life-threatening cold that created mayhem for those travelling over the Christmas holiday.

The storm that arrived earlier in the week downed power lines, littered highways with piles of cars in deadly accidents and led to mass flight cancellations on Saturday.

The storm was nearly unprecedented in its scope, stretching from the Great Lakes near Canada to the Rio Grande along the border with Mexico, with about 60 percent of the US population facing some sort of winter weather advisory or warning.

The frigid temperatures and gusty winds were expected to produce “dangerously cold wind chills across much of the central and eastern US this holiday weekend,” the weather service said, adding that the conditions “will create a potentially life-threatening hazard for travellers that become stranded”.

“In some areas, being outdoors could lead to frostbite in minutes,” it warned.

Adding to the woes were power outages that by late Friday were still affecting more than a million homes and businesses, according to the website PowerOutage, which tracks utility reports.

As millions of Americans were preparing to travel ahead of Christmas, more than 5,700 flights within, into or out of the US were cancelled on Friday, according to the tracking site FlightAware.

Officials said that multiple highways were closed, and crashes killed at least six. Four people died in a massive pileup involving some 50 vehicles on the Ohio Turnpike. A Kansas City, Missouri, driver was killed on Thursday after skidding into a creek, and three others died on Wednesday in separate crashes on icy northern Kansas roads.