The US National Weather Service (NWS) on Thursday warned of "dangerous cold" for much of the country, with a snowstorm expected from late Thursday night into Friday morning.

Temperatures plunged dramatically on Thursday, with one area in the state of Montana, which shares its northern border with Canada, having recorded temperatures as low as -50 degrees Fahrenheit (-45 degrees Celsius).

The weather service warned that an Arctic blast would bring heavy snowfall to the Midwest, the Great Lakes and the Northeast through at least Saturday.

This means that more than 200 million of the country's 335 million will remain under some sort of weather advisory during the Christmas weekend, which is set to be the coldest in the country in decades, according to the weather service.

What's the latest?

As of Thursday morning, Montana, Dakotas, Nebraska, Wyoming were among states experiecing biting cold.

With the snowy part of the storm still to come, NSW predicted that the heaviest snow would likely be seen in the Great Lakes, near the US-Canada border, with 2-4 foot (24-48 inch) snow in total.

For those away from the snow during the weekend, blizzard-like conditions and "dangerous" wind chills could become life-threatening if people found themselves stranded.

The weather service warned about extreme cold temperatures which could lead to frostbites on bare skin in minutes.

What's expected for the holiday weekend?

Holiday plans during one of the year's busiest travel periods are sure to be impacted since trains and flights are canceled through Friday.

More than 2,350 flights had been canceled on Thursday, and another 2,120 flights on Friday have been canceled too, according to flight tracking website FlightAware.

Another 8,450 flights were delayed Thursday, according to the website. 

Amtrak, which is America's passenger rail system, canceled dozens of trains through Christmas, disrupting travel for tens of thousands.

This year's holidays travel chaos comes after the same period in 2021 was marred by COVID outbreaks among airlines' staff that forced thousands of flight cancellations.

Coldest winter in decades

"This is not like a snow day when you are a kid," President Joe Biden warned Thursday after a briefing with federal officials. "This is serious stuff," he said.

Forecasters are expecting a bomb cyclone — when atmospheric pressure drops very quickly in a strong storm — to develop near the US-Canada border.

'Life-threatening' conditions

The NSW forecast that "record-breaking cold and life-threatening wind chills over the Great Plains [would] overspread the eastern half of the Nation by Friday."

The weather agency warned that temperatures would drop between -40 to -70 degrees Fahrenheit (-40 to -56 degrees Celsius), with strong gusts and heavy snow expected to cause damage to infrastructure and disrupt travel.

"Wind chills of this magnitude can cause frostbite in less than five minutes if precautions are not taken, with hypothermia and death also possible from prolonged exposure to the cold," it said.

Authorities have raised concerns that power could be cut due to the storm and asked people to postpone travel. More than 112 million people are estimated to travel 50 miles (80 kilometers) or more during the holiday season.