Thousands of flights have been cancelled as meteorologists warned of a powerful Arctic winter storm in the United States, the BBC reported.

The National Weather Service said temperatures could fall to -45 degrees Celsius by the end of the week in some parts of the country. It described the storm as a “once-in-a-generation” winter weather event.

The weather agency has also warned that frostbite could be a major danger in some metro areas such as the city of Des Moines in Iowa.

“A powerful winter storm and sharp cold front will continue to produce snow from the Midwest and Ohio Valley through the Great Lakes and interior Northeast into this weekend,” the National Weather Service said. “The combination of very cold temperatures and gusty to high winds over much of the central and eastern US will continue dangerous wind chill temperatures behind the sharp cold front.”

Passengers arrive for their flight on Southwest Airlines as flight cancellations mount at the Midway International Airport in Chicago, Illinois on December 22, 2022. | Source: Reuters/Matt Marton.

Weather experts said that the storm could turn into a “bomb cyclone” by Friday. According to the National Oceanic and Atmospheric Administration, a bomb cyclone refers to a fast-developing storm that occurs when a low-pressure system undergoes rapid intensification, with a central pressure that falls at least 24 millibars within 24 hours.

On Thursday, United States President Joe Biden urged Americans to exercise caution during the holiday weekend.

“This is not like a snow day, when you were a kid,” Biden said during a White House briefing on Thursday, according to the BBC. “This is serious stuff.”

A state of emergency was declared in states such as New York, Kentucky, North Carolina, West Virginia, Georgia and Oklahoma.

Authorities in the United States said they were worried about the potential power failures and warned people to take precautions to protect older and homeless people and livestock, reported the Associated Press.

“This event could be life-threatening if you are stranded,” an online post by the National Weather Service in Minnesota said.