The US National Weather Service (NWS) on Thursday warned of "dangerous cold" for much of the country as the Christmas weekend was expected to be the coldest in decades. 

Temperatures plunged dramatically in just a few hours on Thursday. Around 190 million of the country's 335 million population were under some type of weather advisory as a winter storm was forecast. 

'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.