Thursday flight cancellations top 1,000 nationwide, disrupting holiday travel

   (CNN) — More than 1,000 flights have been canceled across the United States, according to the flight tracking site FlightAware, as severe winter weather threatens holiday travel.

As of early Thursday morning, 1,116 flights have been canceled nationwide.

Chicago’s O’Hare International Airport leads the way, followed by Denver International and Chicago’s Midway International. Cancellations at those airports could have a wider impact, since they are busy hubs where travelers often change planes in order to reach other destinations. Thursday is expected to be the busiest pre-Christmas day for travel.

Weather forecasters are predicting a “bomb cyclone,” and the National Weather Service says more than 100 million people are under winter alerts and wind chill alerts — that’s roughly one-third of the US population.

Temperatures in Denver are predicted to plummet to 10 degrees below zero by daybreak Thursday. Chicago could see near-blizzard conditions with snow beginning midday Thursday and continuing into Friday morning.

Many airlines have issued weather waivers, and travelers should check that their flights are still scheduled for takeoff before departing for the airport. Experts are warning flyers to arrive early at the airport in order to beat the crowds.

— CNN’s Dave Hennen contributed to this report.