Airlines canceled 2,274 U.S. flights early Friday as a winter storm shut government offices in Washington, closed schools in Boston and blanketed the rest of the Northeast.

The cancellations marked the fifth day this month with more than 2,000 scrubbed flights, as a jump in coronavirus infections made it especially difficult for airlines to keep operations fully staffed. Since Dec. 24, more than 25,800 have been scrapped, according to FlightAware.com. 

A third of flights at New York City’s LaGuardia Airport already had been canceled by 8:20 a.m. Friday, along with 28% at Boston’s Logan International. John F. Kennedy International in New York City and nearby Newark Liberty International in New Jersey each had 19% canceled.

Southwest Airlines Co. parked 518 flights, or 17% of its service for the day. Alaska Air Group Inc. grounded 19% and JetBlue Airways Corp., 17%.

Typical winter weather disruptions compounded by the pandemic-related staffing issues continue to batter airlines. Alaska has preemptively canceled 10% of its remaining January flights because of “unprecedented” sick calls. JetBlue had already pulled 1,280 flights off its schedule from late December to mid-January.