An ice storm sweeping over parts of the southern U.S. has prompted the cancellations of about 865 domestic flights over the past 24 hours, according to the flight-tracking group FlightAware.com — adding to the seemingly continuous toll of disruptions that has hit flyers over the past year.

The storm was concentrated in the Dallas-Fort Worth metropolitan area, home to both American and Southwest airlines — though with 419 canceled departures early Monday afternoon, Southwest had the lion's share of affected flights, according to FlightAware. An alternative measure of cancellation rates on flight-tracking site Anuvu.com showed 9% of Southwest's flights had been canceled, compared with 6% of American's flights.

In a statement to NBC News, a Southwest Airlines spokesperson described how it is responding to this latest storm: "Based on current and forecasted weather conditions, our Teams have made schedule adjustments to support our operation at airports affected by Winter Storm Mara."

"Above all, our main focus is on the Safety of our Employees and Customers," the spokesperson said.

On Monday, it issued a winter weather waiver for 12 airports in the region that will allow affected travelers to get a refund or rebook for any flights canceled from Jan. 30 to Feb. 1.

The outsize Southwest cancellations come just weeks after a holiday travel meltdown prompted nearly 17,000 flights to be canceled, potentially affecting millions of travelers. Southwest has said a historically disruptive winter storm set off a chain reaction of equipment, technology, personnel and procedural issues that led to the mass cancellations.

Tips for rebooking a flight

To avoid being trapped in a seemingly endless line to rebook at your airline’s terminal, get on the internet immediately and start looking for alternative forms of travel. Experts say Google’s flight search option is the best bet for finding the most up-to-date choices when it comes to getting a new flight, which are also searchable by a number of criteria, including price.

If you’re strapped for cash and are looking to rebook, you’ll still want to attempt to call the airline before or as you wait in line with an in-person rebooking agent. Of note: Not all major airlines have rebooking agreements with other carriers. The ones that do are: Alaska, American, Delta, Hawaiian, JetBlue and United. That ones that do not are: Allegiant, Frontier, Southwest and Spirit.

What your rights are if your flight was canceled

In this situation, you are only entitled to a refund if you don’t take an offer to be rebooked on another flight. That also means you don’t have to accept an airline’s offer of a voucher. According to the Transportation Department: “If an airline cancels a passenger’s flight or makes a significant change in the flight, regardless of the reason, airlines are required to provide a prompt refund to a ticketed passenger, including those with non-refundable tickets, should the passenger choose not to accept the alternative offered, such as rebooking on another flight.”

Unfortunately, you have few rights if your flight is delayed or canceled for reasons outside of an airline's control

According to the U.S. Department of Transportation website, only factors like maintenance or crew problems, cabin cleaning, baggage loading, and fueling count as situations within an airline’s control.

If your flight was delayed for three hours or more or canceled for any of those reasons, you are entitled to a meal or meal cash/voucher and, except for Frontier Airlines, to complimentary hotel accommodations and complimentary ground transportation to and from a hotel for an overnight cancellation. Click here for more information.