A swath of the US woke up on Saturday to the continuing effects of a winter storm that is battering the Northeast with blizzard conditions and keeping temperatures around record lows in parts of the country where freezing cold is rarely a fact of life.

The storm and the Arctic air mass will continue bedevilling most of the central, eastern and southern states for a fourth day with frigid cold and blinding snowstorms, forecasters said. There have been at least a dozen deaths, and tens of thousands of holiday travellers and motorists have been stranded. At one point, more than 1.5 million households were without power.

As the cold front and low-pressure system move offshore, a lake-effect storm will continue to pummel the Great Lakes region, and the bitter cold will remain through Saturday, according to meteorologists.

“When people get up Saturday morning, it’s going to be only Southern Florida that’s above freezing, at least east of the Rockies,” said Marc Chenard, a meteorologist with the National Weather Service. “It’s an event one doesn’t see more than once or twice in a lifetime, something you’ve got to see to believe the impact of the things that are forecast to happen.”

Much of the eastern half of the US is forecast to experience the coldest Christmas Eve in decades, including in places unaccustomed to freezing temperatures, like parts of Louisiana and Florida.

On Friday nearly 6,000 US flights were cancelled, the most of any day this year, according to FlightAware. The cascading effect of earlier cancellations snarled travel even at some airports where the weather was not bad.

That followed nearly 2,700 cancelled flights on Thursday, while just over 1,000 flights have already been cancelled for Saturday, according to FlightAware.

Passenger rail road Amtrak has cancelled dozens of trains through Christmas, disrupting holiday travel for thousands.

Highways in the Midwest faced lengthy delays because of snowy weather or crashes and authorities in parts of Indiana, Michigan, New York and Ohio urged motorists to avoid nonessential travel.

The Federal Aviation Administration (FAA) imposed ground stops or delays for de-icing at a number of US airports because of winter weather.

Transportation secretary Pete Buttigieg told CNN the US aviation system “is operating under enormous strain” with two different storms and high winds affecting airports around the country. About 10 per cent of US flights were cancelled on Thursday, Buttigieg said.

Another 10,400 US flights were delayed on Friday — including more than 40 per cent of those operated by American Airlines, United Airlines, Delta Air Lines and Southwest Airlines — after 11,300 flights were delayed Thursday.

( New York Times News Service and Reuters)