Parts of the US face a “significant Arctic outbreak” for the Thanksgiving holiday, which includes some of the country’s busiest travel days of the year.
“Dangerously cold wind chills” are anticipated over the northern Plains on Thursday by the National Weather Service (NWS).
Meanwhile, parts of the north-east including New England could see heavy snow, and the East Coast is expected to be hit by thunderstorms.
The severe conditions come in a week expected to set records for Thanksgiving travel. Thousands of flights were delayed and dozens cancelled on Wednesday, according to tracking site FlightAware.
The snow expected on Thursday could fall in Maine, New York state and the north Appalachians, said BBC Weather forecaster Elizabeth Rizzini.
The thunderstorms could affect Georgia, plus North and South Carolina, she added.
Stormy conditions are then expected to reach the Midwest on Friday, bringing lake-effect snow and severe thunderstorms.
Lake-effect snow happens when cold air passes over unfrozen and relatively warm waters – in this case in the Great Lakes – causing the air to rise and form clouds that produce snow. Up to 8in (20cm) could fall in some places, the NWS says.
Flight disruption has been reported as holidaymakers attempt to make seasonal journeys. More than 4,500 delays within, into or out of the US were logged by FlightAware on Wednesday. There were 61 cancellations.
The US Transportation Security Administration (TSA) says passenger volumes during this year’s Thanksgiving have already reached record highs.
The busiest days were expected to be Tuesday and Wednesday, before Thanksgiving, as well as the Sunday after the holiday. The TSA expects to screen nearly nine million people at airports during those three days alone.
And a record number of nearly 80 million Americans were expected during the week to travel at least 50 miles (80km) by car. Insurance company AAA said the anticipated increase was due to petrol prices being lower than this time last year.
On the other side of the country, there are dense fog warnings on Thursday for the Pacific north-west and California, as well as freezing fog for Oregon and parts of Washington state, BBC forecaster Elizabeth Rizzini said.
Earlier this week, a winter storm brought heavy snow and high winds for higher elevations in the west. Central California was also hit by another “atmospheric river” event on Tuesday after a similar phenomenon last week. The weather event occurs when water evaporates into the air and is carried along by the wind.
And communities in the Pacific north-west continue to recover from last week’s bomb cyclone, an intense weather event that takes place when air pressure quickly drops off the coast. The storm caused mass flooding and power cuts.
