Thousands of U.S. flights are disrupted by winter storm.

• As a winter storm advanced eastward, over 1,000 U.S. flights were canceled and more than 4,000 were delayed.
• Washington, D.C. was bracing for approximately one foot of snow to fall during the winter storm.
• The disruptions were most severe in and around Washington, D.C., but flights were delayed as far west as Dallas.

Numerous flights were disrupted on Monday due to a winter storm that advanced eastward, causing travel chaos in the eastern U.S.

Over 4,300 US flights were delayed and 1,880 were canceled by 1:45 p.m. ET, according to FlightAware.

According to federal forecasters, 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.

Over 250 flights were canceled at Ronald Reagan Washington National Airport, which is two-thirds of the day's schedule. In contrast, about one-third of the scheduled flights were canceled at each Washington Dulles International Airport and Baltimore/Washington International Thurgood Marshall Airport.

Over 100 flight delays occurred at each of the major New York-area airports, according to FlightAware tallies, while there were also significant slowdowns at other major airports such as Dallas/Fort Worth International Airport and Chicago O'Hare International Airport.

Airlines, including , , waived change fees and fare differences for travelers affected by the storm.