If you were planning to fly Monday or Tuesday this week, you probably know by now that the chances are slim -- especially if you live in or were headed to the northeastern United States. Thanks to a potentially epic blizzard expected to blanket Eastern states, as of 9:30 a.m. Monday morning the airline industry had already canceled more than 4,300 flights in the U.S. for Monday and Tuesday, according to data from FlightAware.

JetBlue, which is headquartered in New York -- where the storm is expected to be particularly severe -- canceled 275 flights, or about a third of its operations, on Monday and another 461 flights scheduled for Tuesday. United Airlines, which has one of its busiest hubs at Newark Liberty Airport, has canceled 244 flights on Monday and 497 flights on Tuesday. Delta, Southwest and American Airlines have grounded a significant number of flights as well.

The airports hardest hit by cancellations are the major hubs dotting the East Coast: New York’s LaGuardia canceled 41 percent of flights for Monday and 36 percent of flights for Tuesday. Newark Liberty Airport in New Jersey has grounded 34 percent of flights on Monday and a whopping 84 percent of flights on Tuesday. Almost a third of all flights departing New York’s JFK International Airport on Monday have been canceled and another 49 percent on Tuesday. Boston’s Logan International Airport and Philadelphia International Airport also face significant cancellations.

In the wake of the storm, a number of airlines have waived their change fees so that passengers can switch flights without a penalty. United Airlines, for example, is waiving change fees for passengers ticketed for Jan. 26 or 27 and flying through its list of affected airports, such as Boston Logan and Newark Liberty. Delta Air Lines has instituted a similar policy, though it notes that changed flights must be rebooked for travel through Jan. 30. To find out whether your carrier has instituted a change fee waiver, visit the airline’s website. Most carriers have posted travel advisory information, along with change waiver details, to their home pages.