Southwest's latest sale offers $39 flights - but you'll have to book soon?

A nationwide sale by Southwest Airlines offers one-way flights starting at just $39 this winter, helping travelers get away from the cold.

There are big savings on flights crisscrossing the country for travel on Tuesdays and Wednesdays from Feb. 6 through May 22. To travel during the sale, a 21-day advance booking is required.

No blackout dates listed for the sale. And while the fares are non-refundable, travelers can cancel and receive a credit to be applied toward a future flight.