Frontier Airlines Offers $39 Flights On Select Routes In Extended Flash Sale

'Tis the season for flash sales on flights.

As such, Frontier Airlines has extended its "Thank You" sale through Friday, June 5. One-way, nonstop flights start as low as $39, and there are chances to win free roundtrips with the airline.

Some of the best deals we found included flights from Washington, D.C. to Miami for $39, from Atlanta to Denver for $39 and from New York to Atlanta for $89.

Destinations are somewhat limited, perhaps because the sale has been going on for a while already. But if you have a specific trip in mind -- or you're flexible with your destination choices -- then it's certainly worth a look.

The sale is for flights between June 13 and Oct. 20, 2015. Each deal is available for flights on certain days only; all of the deals we saw excluded Fridays and Sundays.

But hey: for $39, we'd fly ANY day.