Airplanes on the tarmac during a snow storm at Ronald Reagan Washington National Airport in Arlington, Virginia, US, on Monday, Jan. 6, 2025. Ting Shen | Bloomberg | Getty ImagesThousands of flights were disrupted Monday as a winter storm moved eastward, snarling air travel in the eastern U.S.By 5:45 p.m. ET, more than 6,900 U.S. flights were delayed while more 2,130 were canceled, according to flight tracker FlightAware.The storm, which was moving from the Ohio Valley to the mid-Atlantic, was set to dump as much as a foot of snow in the Washington, D.C., area, though cold weather stretched through the southern U.S., according to federal forecasters.More than 300 flights, or 80% of the day’s schedule, were canceled at Ronald Reagan Washington National Airport, while about a third of the scheduled flights were canceled at each Washington Dulles International Airport and Baltimore/Washington International Thurgood Marshall Airport.Read more CNBC airline newsThese airlines were the most on time in 2024Airlines’ wild 2024: From Boeing troubles to a bankruptcy and a mergerAmerican Airlines cracks down on boarding line cutters with new technologyEach of the major New York-area airports had about 200 flight delays, FlightAware tallies showed, and there were significant slowdowns at other major airports like Dallas/Fort Worth International Airport and Chicago O’Hare International Airport.United, Southwest, American and other airlines waived change fees and fare differences for travelers affected by the storm.Don’t miss these insights from CNBC PROHow to invest $50,000 in 2025 to maximize returns with the lowest riskHow to invest $50,000 in 2025 for the biggest returns with only modest riskThese stocks will be the biggest Nasdaq losers of 2025, according to analystsA buying opportunity into the new year has opened up, says Tom Lee …