Wednesday's disruptions come in addition to 1,600 cancellations Tuesday and 2,100 on Monday, according to flight tracking site FlightAware. Fliers should get a break on Thursday with few flights expected to be affected by weather.
Most of Wednesday's canceled flights were from the New York-area airports, Boston, Chicago, Philadelphia, and Washington. Regional airline Cape Air alone canceled more than 200 flights, including nearly every flight planned from airports in Massachusetts.
United Airlines said the disruptions also affected flights in the Midwest, including Chicago and Cleveland. United and other airlines are allowing passengers to change their tickets without the usual change fees.