As a dangerous winter storm reaches the Northeast, airlines have already canceled thousands of flights.

More than 3,300 U.S. flights have been canceled for Sunday, Feb. 22, and over 5,000 others have been delayed as of 5 p.m. ET, according to flight-tracking website FlightAware. Trying to get ahead of the impact, airlines have already canceled more than 4,800 U.S. flights scheduled for Monday, Feb. 23.

Those numbers are expected to climb as the nor'easter is set to dump about 20 inches of snow in some areas.

Airlines began offering travel waivers to help customers avoid flight disruptions.

“It’s about keeping the airport, the environment clean and ready, snow removed, and then it’s about having our pilots, our flight attendants and our airplanes all lined up so we can get our customers onboard and move them to where they want to be,” John Laughter, Delta Air Lines' chief of operations, previously told USA TODAY.

As the storm closes in and then starts hitting airports, some flights may be canceled for a day or two after the weather clears, as airlines work to get all their aircraft and crews back into place for normal operations.

If you absolutely have to travel, be prepared to roll with the punches. More flights are likely to get delayed or canceled as the storm progresses. Research your rebooking options and alternative itineraries in advance, and take advantage of airlines' self-service tools to avoid long lines at airport agent desks or long hold times on the phone.

"Speed is going to be critical," Katy Nastro, a travel expert at Going, previously told USA TODAY. "We want those who are flying to make alternative plans much sooner rather than later so they ensure they get a rebooking that works best for them. There will not be an endless supply of seats to reaccommodate you on ... there is no time like the present to give yourself the best odds at a decent rebooking."

It's also a good idea to pack extra provisions for yourself if you're heading to the airport.

According to Matas Cenys, head of product at eSim company Saily, bringing extra clothes and doses of any medication you may be taking, as well as essentials like charging cables, could come in handy if you get stuck.

Travel waivers by airline

Terms vary, but these waivers generally allow travelers to rebook without penalty or get flight credit if they cancel their trips.

Customers can find details, including impacted airports and key dates, on each carrier's website linked below.

Alaska Airlines

American Airlines

Avelo Airlines

Breeze Airways

Delta Air Lines

Frontier Airlines

JetBlue

Southwest Airlines

Spirit Airlines

United Airlines

What happens if a flight gets canceled?

Airlines will automatically rebook you on another flight if your flight is canceled. Typically, it’s on the same airline, but depending on the reason for the cancellation and carrier, some may be able to rebook you on a partner airline.

If your flight is canceled for reasons within the carrier’s control – say, due to staffing or aircraft maintenance – you’re entitled to a meal if you have to wait more than three hours for the next flight. If you end up stranded overnight, most airlines will also cover your hotel and ground transportation if the cancellation was within their control.

Weather is notably outside of airline control.

If your flight is canceled for any reason and you choose to no longer fly, Department of Transportation rules require the airline to offer you a refund, regardless of ticket type.

You can find airline-specific information on the DOT’s Airline Customer Service Dashboard.

What happens if my flight is delayed?

Airlines are required to get you to your destination, but they don’t owe you anything else for delays due to weather or anything else outside of their control.

It’s a different story for significant delays due to issues within their control.

All airlines will rebook customers on their same airline for significant delays (typically at least three hours) within their control, but some will also book customers on partner carriers.

Airlines will also cover meals for controllable delays at least three hours long. Most airlines will also cover a hotel stay and ground transportation for overnight delays within their control.

Again, weather is outside of airline control.

Additional details can be found on the DOT dashboard. It’s worth noting that U.S. regulators don’t require cash payments for delays. Also, even when it’s not required, airline customer service representatives may have the power to provide meal vouchers, mileage credit or other compensation for your trouble, on a case-by-case basis. (USA Today, but headline rejigged)