If you were planning to travel to the Northeast this week, you’ll probably need to change your itinerary, as more than 1,000 flights have already been canceled in advance of a massive snowstorm..

A look at FlightAware’s cancellation listings shows that today, March 13, is already sporting nearly 2,400 delays and more than 1,280 cancellations — and it’s not even 10 a.m. yet on the East Coast. That number is likely to keep going up.

It’s Chicago that’s hardest-hit today: 30% of all flights leaving Midway and 17% of all flights leaving O’Hare have already been halted.

Tomorrow, March 14, is also looking pretty brutal for the East Coast, especially for the Baltimore-Washington area. FlightAware reports that about 1,330 flights have already been cancelled for tomorrow, and that number rises on every refresh.

Southwest alone has already cancelled more than 880 flights for tomorrow, and 68% of all flights out of Baltimore-Washington Airport (many of them Southwest) are already scrapped, too. Providence and Manchester (NH) are both past the 40% cancellation mark, nearly a quarter of flights from Hartford have been scrapped, and New York’s LaGuardia and D.C.’s Reagan National are also already both creeping towards the 20% cancellation mark for tomorrow — and all those numbers go up on every refresh, too.

Most airlines are offering some kind of fee waiver or free rebooking for flights into or out of affected areas today and tomorrow:

American Airlines: Customers flying into or out of affected airports in a specific date range can change their trips to travel either by March 15 or March 17 (depending on airport) without incurring change fees.

Delta: Customers traveling through any of the affected airports on March 14 or 15 can rebook for flights through March 17 without paying a change fee.

Frontier: Customers whose flights to through the affected airports can rescuedule through April 7 with change fees and most travel restrictions waived.

JetBlue: Customers flying into or out of affected cities can rebook for travel any time Monday, March 13, through Thursday, March 16. Customers with cancelled flights can also opt for a full refund.

Spirit: Customers flying throughj affected airports can travel at the same fare, without paying modification fees, through March 16 or March 18, depending on city.

Southwest: Customers holding reservations into or out of affected airports on specific dates can rebook or travel standby within 14 days of their original trip without paying any additional charge.

United: Customers traveling through the affected cities can rebook through March 17 without incurring a change fee.

These summaries are accurate as of 9:30 a.m. EDT on March 13, 2017; check your own airline if you’re traveling, though, because with weather, everything is subject to change.

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