Over 23,000 US flights were affected Monday by severe winter storms

Subfreezing temperatures, bursts of heavy snow and strong wind gusts battered the U.S. over the holiday weekend, causing thousands of flight disruptions. Over 2,400 U.S. flights were canceled and more than 21,000 delayed Monday as of 3:15 p.m, according to flight-tracking website FlightAware.

Southwest Airlines was hit the hardest with 717 cancellations or 18% of its schedule, followed by United Airlines with 339 cancellations or 13% of its schedule.

If your flights are impacted by the weather, it's important to know your rights. You may be entitled to compensation from the airline or even a full refund, depending on the situation.

The Department of Transportation has an airline customer service dashboard to help travelers understand the basics, and the commitments outlined there are legally binding on the airlines. The general rule of thumb is you're entitled to a refund if your flight is canceled for any reason and you choose not to travel on the alternative flights you're offered. For delays, airlines are required to compensate you in the event of delays they cause, like those that result from crew scheduling or mechanical issues. But "uncontrollable delays" like those that result from weather or air traffic control requirements are not usually eligible for compensation.

Airlines also usually offer increased flexibility to rebook in advance of severe weather if you think your plans may be affected.

Airline weather waivers

The following airlines are offering change waivers to allow you to adjust your travel plans in the coming days. Click each airline to see the policy details.

• Alaska Airlines
• American Airlines
• Delta Air Lines
• Southwest Airlines
• United Airlines
• JetBlue
• Spirit Airlines

What happens if my flight is canceled?

For any cancellation, you're entitled to a refund if you choose not to travel. If you accept alternative flights, however, your entitlements change.

For example, if American, Delta, Hawaiian or United cancel a flight for controllable reasons, they're committed to:

• rebooking passengers on the same airline or a partner airline, at no extra cost
• providing a meal or cash or voucher for a meal when the cancellation results in a passenger waiting at least three hours for a new flight
• providing complimentary hotel accommodations for any passenger affected by an overnight cancellation 
• providing complimentary ground transportation to and from a hotel for any passenger affected by an overnight cancellation

Alaska and JetBlue offer the same, plus some additional compensation.

Allegiant, Frontier, Southwest and Spirit do not book passengers on partner airlines. Additionally, Frontier does not offer hotel accommodations and related transport.

What happens if a flight is delayed?

"There are no federal laws requiring airlines to provide passengers with money or other compensation when their flights are delayed," according to the Department of Transportation, but U.S. carriers have committed to various levels of compensation for significant delays. Each airline, however, defines significant delays differently.

If a flight is significantly delayed for reasons within their control, Alaska, American, Delta, Jet Blue and United offer:

• rebooking passengers on the same airline or a partner airline, at no extra cost
• providing a meal or cash or voucher for a meal when the delay results in a passenger waiting for at least three hours for departure
• providing complimentary hotel accommodations for any passenger affected by an overnight delay
• providing complimentary ground transportation to and from a hotel for any passenger affected by an overnight delay

Alaska and JetBlue offer the same plus some additional compensation.

Allegiant, Frontier, Hawaiian, Southwest and Spirit do not rebook travelers on partner airlines. Frontier doesn't offer hotel accommodations or related transport either.

How to check the reason for your flight delay or cancellation 

There usually isn’t a central repository for the cause of airline delays or cancellations, but carriers will typically advise passengers what’s behind a schedule change.

Your best bet for finding out what happened is to look at your airline’s app or any emails you get from the carrier about your flight. If you’re already at the airport, you can speak to a gate agent or other customer service employee.

The FAA also has a website that lists general air traffic restrictions by airport, and that can be a good way to find out if it’s weather or air traffic control staffing problems delaying your flight.

How do you request additional compensation from airlines during controllable delays and cancellations?

Many times, you’ll have to speak to a customer service agent or may even have to wait in line at the airport to get things like hotel and meal vouchers.

Refunds or credits can often be processed over the phone or through airline customer service chat features, and it may be worth waiting a few days for the call volume to drop if all you’re looking for is a refund and don’t need to be rebooked. Airlines rarely compensate you after the fact if you've paid out of pocket for a hotel, meal or ground transportation as a result of a delay, but a travel insurance policy often will, which is why getting one can be such a big benefit. In the very few cases when airlines do offer compensation for out-of-pocket expenses, they'll outline what you need to do to claim it, as Southwest did during its meltdown over the winter.

How else can I protect myself when I travel?

Especially during the winter when storms can snarl flights, it's a good idea to take out travel insurance. That will give you an extra measure of security if something goes wrong.

Contributing: Eve Chen, USA TODAY, The Associated Press