WASHINGTON, D.C.: As a powerful winter storm snarls air travel across much of the United States, thousands of passengers are discovering that bad weather doesn't just disrupt flights, it also tests how well travelers know their rights.

Snow, sleet, and ice are expected to affect roughly half the U.S. population, with forecasters warning of widespread power outages and damage in hard-hit areas that could rival a hurricane. Airlines have already canceled thousands of weekend flights, and more disruptions are likely.

Here's what travelers should know as winter weather triggers delays and cancellations.

Watch for Airline Travel Alerts

When airlines anticipate weather-related disruptions, they often issue travel waivers that let passengers rebook for later dates without paying change fees. Travelers should search online for their airline's name along with terms like "travel alerts" or "travel waivers" to see if those options are available.

American Airlines said it is waiving change fees for passengers affected by the storm that brought freezing rain to parts of Texas on Friday. The carrier has canceled more than 1,200 flights scheduled to depart on January 24, according to aviation analytics firm Cirium. It also added more than 3,200 extra seats on flights to and from Dallas-Fort Worth International Airport through at least January 25.

Check Flight Status Before Leaving

Passengers should confirm their flight's status using the airline's mobile app or website before heading to the airport. Weather-related cancellations can occur hours or even days before departure.

If your Flight is Canceled

Travelers already at the airport should line up to speak with a customer service representative. Those elsewhere should contact the airline by phone or online. It can help to research alternate flights while waiting to talk with an agent.

Most airlines will rebook passengers on a later flight at no extra charge, though availability depends on open seats.

Can Airlines put you on Another Carrier?

Airlines are not required to book passengers on competing airlines. Some large carriers may rebook travelers on partner airlines, but that is not guaranteed.

Refund Rules

If a flight is canceled and a passenger no longer wants to travel — or finds another way to reach their destination — airlines are legally required to issue a refund, even for nonrefundable tickets. The reason for the cancellation does not matter.

Passengers are also entitled to refunds for unused extras such as baggage fees or seat upgrades. Airlines may offer travel credits, but travelers have the right to insist on a refund.

According to the U.S. Department of Transportation, credit card refunds must be processed within seven business days after a passenger declines rebooking or a voucher. Refunds paid by cash or check are due within 20 calendar days.

What Airlines Must and Don't Cover

U.S. airlines are not required to pay for meals or hotels when flights are canceled or delayed due to "uncontrollable" events like severe weather.

However, airlines do have specific obligations for disruptions they can control, such as maintenance problems, crew shortages, or system outages. The Transportation Department tracks those commitments and can hold airlines accountable.

Extra Tips

Kyle Potter, executive editor of Thrifty Traveler, advises travelers to consider booking backup flights when forecasts look risky. Some airlines allow full refunds if tickets are canceled within 24 hours of booking.

Customer service lines can become overwhelmed during significant storms. Travelers with elite frequent-flyer status should use priority phone numbers. Another option is calling an airline's international support line, where agents can often assist with rebooking.