WASHINGTON — If you’re planning for a summer vacation, then Southwest Airlines has a deal for you: round-trip flights under $100, but you better act fast because it all ends June 7.

It is part of Southwest’s twice-a-year fare sale. Flights start at $49 one-way from all three D.C.-area airports.

Of course, as with most deals this good, some restrictions apply.

The sale only covers flights from Aug. 21 through Dec. 12, or from Sept. 5 through Dec. 6 if you want to go to San Juan, Puerto Rico.

The sale does not include domestic flights on Fridays and Sundays. Dates around Labor Day and Thanksgiving are also blacked out if you’re looking to fly in the U.S. The fares are only valid on nonstop flights.

You can find more information on Southwest’s website.

The sale runs through 11:59 p.m. in the time zone of the city you’re flying out of on June 7.

On Southwest’s website you can find a list of destinations that you can head to from Reagan National Airport, Dulles International Airport and BWI-Marshall Airport.