More than 750 U.S. flights canceled Monday after challenging holiday weekend

Thousands more flights were cancelled or delayed Monday across the world as airlines continued to struggle with staffing issues during the busy holiday season.

Domestically, 755 flights within, into or out of the U.S. were canceled as of 8 a.m. eastern Monday, according to the tracking site FlightAware. An additional 938 flights in the U.S. were delayed.

Globally, more than 2,200 flights were canceled Monday as Christmas travelers sought to return home. Nearly 5,000 international flights were experiencing delays.

United Airlines canceled 87 flights as of 8 a.m. Monday, and American canceled 77.

The omicron variant, the dominant coronavirus variant currently infecting people in the U.S., is being blamed for much of the staffing shortages. Omicron is significantly more transmittable than earlier variants but early studies indicate its symptoms are far less severe on most individuals who contract it.

Bad weather in certain locations also is leading to cancellations.

JetBlue canceled 66 flights as of Monday morning, followed by Delta with 56 cancellations. Southwest has canceled 48 flights; Spirit, 36.

On Sunday, more than 1,500 flights within, into or out of the U.S. were canceled, while more than 3,200 were canceled globally.