Flight cancellations are continuing to mount today as the U.S. is being hit with dangerous winter weather from a storm moving across the country.

Airlines have canceled more than 10,00 U.S. flights for Sunday, according to the flight-tracking site FlightAware. That’s the most for a single day since the start of the COVID-19 pandemic and more the double the number of U.S. flights that were canceled for Saturday.

The National Weather Service says the storm is bringing widespread heavy snow, sleet and freezing rain from the Southern Rockies to New England through Monday.