CHICAGO (NewsNation) —  An arctic blast surged across a wide swath of the U.S. on Wednesday, gripping much of the nation with bitter cold and life-threatening wind chills ahead of a powerful winter storm expected to complicate holiday travel for millions of Americans.

So far Thursday, more than 1,200 flights are canceled and nearly 1,000 are delayed across the nation, according to FlightAware.

At least 145 flights into or out of Denver International Airport were canceled Wednesday as the city was hit with snow, gusty winds and freezing temperatures, according to FlightAware, a flight tracking company. At least 219 flights into or out of Denver were expected to be canceled Thursday.

In Chicago, 1 in 5 people are expected to fly this holiday through the city’s airports as a winter storm warning is in expected to start in the Chicagoland area Thursday night. FlightAware estimates at least 364 flights to be canceled Thursday at Chicago’s O’Hare and Midway airports.

Earlier this week, those two airports said they had 350 pieces of snow removal equipment and 400,000 gallons of pavement de-icing fluid on hand for the storm.

Forecasters predict an onslaught of heavy snow, ice, flooding and powerful winds from Thursday to Saturday in a broad swath of the country, from the Plains and Midwest to the East Coast. A surge of arctic air will follow. The Christmas weekend could be the coldest in decades.

The National Weather Service said Wednesday the storm was so large and encompassing that around 190 million people are currently under some type of winter weather advisory.

To alleviate some stress, American, Delta, United Southwest, Spirit, JetBlue and Frontier are waiving change fees and offering travelers the option of choosing new flights to avoid the bad weather.

Travel experts recommend consumers read the fine print carefully. Airlines might charge the difference in fares if passengers book beyond a certain window, for example.

Bus and train travelers were also bracing for cancellations and delays.

As of late Wednesday, Amtrak had canceled train service on around 30 routes, some through Dec. 25. Greyhound canceled bus service on 25 routes for Wednesday and Thursday, including service from Las Vegas to Denver, Denver to St. Louis and Chicago to Minneapolis, Memphis and Nashville.

The weather added uncertainty to what was expected to be a busy travel season. AAA estimates that nearly 113 million people would travel 50 miles from home or more between Dec. 23 and Jan. 2. That’s 4% higher than last year, although still short of the record 119 million in 2019.

Most planned to travel by car. About 6% will travel by air, AAA said. Either way, many travelers found themselves hastily changing their itineraries.

Airport vendors and restaurants told NewsNation they’ve ordered more food than usual to prepare for travelers getting stuck at their airports.

For those driving, the National Weather Service (NWS) urges drivers to make sure their vehicles are stocked with the supplies they need in case of a winter emergency. 

Drivers should winterize their vehicles and prepare a winter storm survival kit including:

• Warm clothing: extra hats, coats, mittens, blankets, emergency hand warmers
• Cellphone charger, portable battery booster
• Windshield scraper and brush
• Shovel
• Flashlight/signal light with extra batteries
• Water and snack food to last 36 hours
• First aid kit with any necessary medications and a pocket knife
• Tow chains or rope
• Compass and road map