Winter weather can upend even the best-laid travel plans, but one less thing to worry about is losing money if your flight is canceled: U.S. airlines are required to provide refunds.

A major, dayslong winter storm is threatening to bring snow, sleet, ice and extensive power outages to about half the U.S. population. Thousands of weekend flights already have been canceled, and forecasters warn that catastrophic damage, especially in areas pounded by ice, could rival that of a hurricane.

Here’s a guide for travelers as flight disruptions start stacking up:

Keep an eye on weather forecasts

When airlines expect bad weather to create problems for flights, they often give travelers a chance to postpone their trips by a few days without having to pay a fee. Search online for your airline’s name and “travel alerts” or similar phrases to look for possible rescheduling offers.

American Airlines, for example, said it is waiving change fees for passengers impacted by the storm, which brought freezing rain to parts of Texas on Friday. The Texas-based airline has canceled more than 1,200 flights scheduled to depart Saturday, according to aviation analytics firm Cirium.

American also added extra flights to and from Dallas-Fort Worth International Airport through at least Sunday — totaling more than 3,200 additional seats.

Check before going to the airport

Use the airline’s app to make sure your flight is still on before heading to the airport. Cancellations can happen hours or even days before departure time.

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.

When will I get my refund?

If you paid with a credit card, a refund is due within seven business days after you decline an offer from the airline for another flight or a voucher, and within 20 calendar days if you paid for the ticket with a check or cash, according to the U.S. Department of Transportation.

What else will my airline cover?

U.S. airlines aren’t required by the Transportation Department to compensate passengers for meals or lodging when an airline cancels or significantly delays a flight during an “uncontrollable” event like bad weather.

Each airline, however, does have its own policies for assisting passengers who are stranded by a so-called “controllable” flight cancellation or long delay. These include disruptions caused by maintenance issues, crew shortages or computer outages that halt operations. The Transportation Department can hold airlines accountable for these commitments and maintains a website that lets travelers see what each airline promises if a major disruption is their fault.

Other tips

If the weather forecast is troubling, Kyle Potter, executive editor of Thrifty Traveler, suggests looking into booking a backup flight. Some airlines stand out as potential backups, Potter says, because they let customers get a full refund as long as they cancel within 24 hours of booking.

The customer service phone lines will be slammed if flight cancellations and delays start stacking up during a bad storm. If you’re traveling with someone who has a higher frequent-flyer status, call the airline using their priority number. Another trick: Look up the airline’s international support number. Those agents can often rebook you just the same.

Rio Yamat, The Associated Press