"The vast majority of these cancellations are to and from locations up in New England and New York State," said Philadelphia International Airport spokesperson Diane Gerace.
Gerace says weather issues have caused cancelled flights - arriving and departing - from the major hub, leaving thousands of traveling plans up in the air.
And it could get worse.
"We could potentially see a domino effect where you are going to see more cancellations piling up as well as delays," she said.
Gerace urges passengers to not only plan ahead, but to remember that, "whenever you're scheduled to fly, check with your carrier. Especially when there is inclement weather going on."