Widespread snow, sleet and freezing rain threatened nearly 180 million people — more than half the U.S. population — in a path stretching from the southern Rocky Mountains to New England, the National Weather Service said Saturday night. After sweeping through the South, forecasters said the storm was expected to move into the Northeast, dumping about 1 to 2 feet (30 to 60 centimeters) of snow from Washington through New York and Boston.

More than 14,100 flights have been canceled across the U.S. since Saturday, according to flight-tracking site FlightAware. Over 10,000 of those were scheduled for Sunday.

Ronald Reagan Washington National Airport warned travelers on its website of widespread flight cancellations. Nearly all of its departing flights scheduled for the day — 420 flights, or 99% — have been canceled.

Significant disruptions have hit major airport hubs in Dallas-Fort Worth, Charlotte, Philadelphia and Atlanta, home to the nation’s busiest airport, as well as New York’s John F. Kennedy International Airport and LaGuardia Airport.

American Airlines had canceled over 1,400 flights for Sunday, about 45% of its scheduled flights for Sunday, according to FlightAware. Delta Air Lines and Southwest Airlines each reported over 1,200 cancellations for the day, while United Airlines had more than 860. JetBlue had more than 570 canceled flights, accounting for roughly 71% of its schedule for the day.

My flight was canceled, now what?

If you’re already at the airport, get in line to speak to a customer service representative. If you’re still at home or at your hotel, call or go online to connect to your airline’s reservations staff. Either way, it helps to also research alternate flights while you wait to talk to an agent.

Most airlines will rebook you on a later flight for no additional charge, but it depends on the availability of open seats.

Can I get booked on another airline?

You can, but airlines aren’t required to put you on another carrier’s flight. Some airlines, including most of the biggest carriers, say they can put you on a partner airline, but even then, it can be a hit or miss.

Am I owed a refund?

If your flight was canceled and you no longer want to take the trip, or you’ve found another way to get to your destination, the airline is legally required to refund your money — even if you bought a non-refundable ticket. It doesn’t matter why the flight was canceled.

The airline might offer you a travel credit, but you are entitled to a full refund. You are also entitled to a refund of any bag fees, seat upgrades or other extras that you didn’t get to use.