Plunging temperatures wreaking havoc across the US and Canada can lead to frostbite on bare skin in only five to 10 minutes, experts are warning.

A powerful Arctic winter storm has placed more than 135 million people under weekend weather alerts ahead of the busiest travel days of the year.

The alerts stretch from coast to coast and reach as far south as the US-Mexico border and Florida, the Sunshine State.

Major airports have cancelled thousands of flights as the storm intensifies.

The cold snap could bring the iciest Christmas in decades, say forecasters.

Holiday travel upended as forecasters warn of ‘bomb cyclone’

Thousands of flights were canceled and homeless shelters were overflowing Thursday amid one of the most treacherous holiday travel seasons the U.S. has seen in decades, with temperatures plummeting 50 degrees Fahrenheit in some areas and forecasters warning of an impending “bomb cyclone” that could make conditions even worse before Christmas.

The frigid air was moving through the central United States to the east, with windchill advisories affecting about 135 million people over the coming days, weather service meteorologist Ashton Robinson Cook said Thursday. Places like Des Moines, Iowa, will feel like minus 37 degrees, making it possible to suffer frostbite in less than five minutes.

“This is not like a snow day when you were a kid,” President Joe Biden warned Thursday in the Oval Office after a briefing from federal officials. “This is serious stuff.”

Forecasters are expecting a bomb cyclone — when atmospheric pressure drops very quickly in a strong storm — to develop late Thursday and into Friday near the Great Lakes. That will stir up blizzard conditions, including heavy winds and snow, Cook said.