More flight cancellations marked the last day of the year-end holiday travel rush amid poor weather and soaring COVID-19 cases driven by the omicron variant.

On Sunday, airlines have already canceled more than 2,100 domestic and international flights across the country, according to flight tracker FlightAware.

Flight cancellations have increased steadily since Christmas Eve, hitting a new peak Saturday as millions of Americans return from their holiday travel. On Saturday, more than 2,700 Saturday flights were canceled, bringing the total since Christmas Eve to more than 14,000 canceled flights.

As of Sunday morning, over 2,100 flights have been canceled for the day due to weather and staff shortages, according to Flight Aware. The flight tracking service shows that the largest number of cancellations at a single airport by any airline has been at Chicago’s O’Hare Airport, where 265 flights have been canceled.