A Winter storm The crisis spreading across much of the US is disrupting travel as thousands of flights were either canceled or delayed on Monday morning. Amtrak has also canceled several routes along the East Coast and Mid-Atlantic states.

As of Monday morning, about 34 million Americans are under warnings for winter storms stretching from Illinois to mid-Atlantic states like New Jersey and Delaware. The storm, dubbed Winter Storm Blair, is bringing a combination of snow, ice and plunging temperatures across the U.S., while also causing devastating damage to motorists with icy roads and blizzard-like weather.

Airlines canceled nearly 1,500 flights within, to or from the U.S. as of 8 a.m. ET on Jan. 6, while another approximately 900 flights were delayed, according to data from flight tracking service FlightAware. Southwest had the most cancellations, with about 360, followed by American Airlines and Republic, each with 176 flight cancellations, the data shows.

Amtrak, meanwhile, canceled several trains, saying the disruptions were “intended to ensure the safety of Amtrak customers and employees due to predicted winter weather.” The train service said that while the Acela runs between Boston and Washington, D.C., several other routes between Washington and New York and between other mid-Atlantic cities have been canceled.

The storm’s reach will impact the mid-Atlantic states on Monday, with a severe freeze expected as far south as Florida. Winter Storm Blair is expected to move offshore into the Atlantic Ocean on Tuesday.

While the polar vortex of extremely cold air usually stays confined around the North Pole, it sometimes escapes or extends into the United States, Europe or Asia, creating the intense cold of Winter Storm Blair. Studies have shown that a rapidly warming Arctic is partly responsible for the increasing expansion or migration of the polar vortex.

contributed to this report.