Airlines canceled nearly 2,000 U.S. flights scheduled for Thursday and Friday, disrupting holiday travel for thousands, as an Arctic blast surged across a wide swath of the country ahead of a powerful winter storm.

The extreme weather coincided with the start of a holiday travel season shaping up as one of the busiest in decades.

Total cancellations within, into, or out of the United States were 1,239 as of 8 a.m. ET on Thursday, as per tracking website FlightAware, and an additional 699 flights for Friday were scrapped.

Last year's holiday period was marred by an outbreak of COVID-19 among staff that forced airlines to cancel many flights.

U.S. airlines including Delta, United Airlines and American Airlines said on Tuesday they were waiving change fees and fare differences for passengers in a range of affected areas.

American Airlines said on Wednesday it was continuing to monitor the winter storm, which is expected to impact Midwest, Northeast and East Coast airports this week, and had canceled about 80 flights as of 8 a.m. ET.

Southwest Airlines had canceled 459 flights.