More than 2,400 US flights are canceled as Omicron and adverse weather continues to cause travel chaos

Americans are left stranded as airlines cancel flights due to staff shortages brought about by a rise in Covid-19 cases

Travelers queue up at the Southwest Airlines curbside check-in area at Denver International Airport on 26 December (AP)

More than 2,400 US flights were canceled on Sunday as the spread of the Omicron Covid-19 variant and adverse weather conditions continued to cause travel chaos over the holiday season.

A total of 2,449 flights within, into or out of the US on Sunday had been canceled by 4pm ET while 5,251 additional US flights were subjected to delays, according to tracking website FlightAware.com.

Key US travel destinations Chicago and Denver were the worst-affected airports worldwide to be hit by cancellations, with 276 outgoing and 20 incoming flights canceled at Chicago O’Hare International and 141 outgoing and 172 incoming canceled at Denver International.

The two states are among those impacted by wintry weather while a large storm is now also threatening to add further disruption as it brings heavy snow and ice across the Midwest and the Rockies.

Several airlines have also been forced to cancel flights due to staff shortages caused by the rise in Covid-19 cases.

The US is currently dealing with the rapid spread of the new Omicron variant, reaching almost 500,000 new infections every day, and pilots and cabin crew are testing positive and being forced to quarantine.

Flight cancellations have been escalating since Christmas Eve, reaching a peak on the first day of the year.

New Year travel was off to a tumultuous start when more than 2,700 US flights were canceled on 1 January as Americans planned to head home from their New Year’s celebrations.

A total of 593 US flights have already been canceled for Monday, leaving many stranded just as they are returning to work from an extended Christmas break.

While travel chaos is being felt across the globe, the US appears to be bearing the brunt of it, making up more than half of the total 4,102 flights canceled globally on Sunday.

The flurry of cancellations has put a dampener on the holiday season which is typically a time of increased travel as Americans visit family and friends and take vacations from work.

Skywest was the worst US airline affected on Sunday, with the regional Utah-based carrier axing 21 percent of all its flights.

JetBlue grounded 16 percent of its scheduled flights, Southwest 11 percent, Spirit 10 percent and Delta 6 percent.

The problem is expected to persist into the month, with JetBlue already scrapping around 1,280 flights from its schedule through to 13 January.

Some airlines are trying to limit the number of cancellations with United Airlines offering pilots three times their usual wages to take on extra flights in January.