Clearing weather over much of the eastern United States raised hopes that air-travel disruptions will ease after a dreadful start to the new year.

By early Tuesday evening on the East Coast, airlines had scrubbed about 1,500 flights for the day. That’s a very high number but well below Monday’s disruptions, which included more than 3,200 canceled flights.

Southwest Airlines canceled about 400 flights, or 12% of its schedule Tuesday.

Airlines had already canceled nearly 500 U.S. flights for Wednesday, according to FlightAware.

The number of canceled flights began rising Dec. 24, and several airlines blamed it on crew shortages due to the spreading omicron variant of COVID-19. Over the weekend, the sickouts were compounded by winter storms that swept across the country.

About 2,700 U.S. flights were canceled on Saturday and a similar number were grounded Sunday. Thousands more were delayed. In all, about 20,000 U.S. flights have been canceled since Christmas Eve, according to FlightAware figures.

Airlines often canceled flights long before storms hit, based on weather forecasts. Airlines think that by operating a reduced schedule they will avoid having planes and crews trapped in the wrong cities, but it frustrates passengers whose flights get canceled while it’s still sunny outside.