More than 1,000 Monday flights into or out of the United States have been cancelled due to a severe winter storm, with about half of those coming from Southwest Airlines Co (LUV.N).

A total of 1,019 flights were cancelled as of 6:00 pm ET, according to flight-tracking service FlightAware.

Low-cost carrier Southwest earlier this month faced US government backlash for cancelling 16,700 flights over the holidays as it grappled with bad weather and outdated technology. The company has scrapped about 12% of its Monday schedule, while American Airlines Group Inc (AAL.O) has cancelled 6%, or 200 flights.

The fresh cancellations come as the US aviation sector recovers from a nationwide ground stop imposed by the Federal Aviation Administration (FAA) over a computer issue.

For Tuesday so far, 797 flights are scheduled to be cancelled into or out of the United States.

Southwest Airlines and other major U.S. airlines have issued winter weather waivers. A waiver allows customers to change their itinerary with no fare differences if they remain in the same cabin as originally booked.