Frontier Airlines is offering a slew of cheap flights this week, including some at an eye-popping $29, to cities such as Orlando, Denver and Atlanta. But there is a catch or two to know.

The sale is tailored for for last-minute, end-of-summer getaways, with the flights available between Aug. 4 and Aug. 30. Those taking advantage need to move quickly, as these flights must be booked by this Wednesday, Aug. 2.

It covers a host of select routes, with Nashville to Orlando, Kansas City to Denver and Cleveland to Atlanta all going for $29 one way to members of Frontier's Discount Den program.

If you're not a member of Frontier's program, no worries: Those flights still go for $39.

Remember that Frontier is a bare-bones budget airline, though. The fares themselves are cheap, but the airline may ding you for extras such as carry-on bags and reserved seats.

See the more than 50 routes going for less than $50 at Frontier's site. These are the cheapest routes listed for as little as $29 to $39:

Atlanta to Cincinnati

Atlanta to Cleveland

Bismarck to Denver

Cincinnati to Atlanta

Cleveland to Atlanta

Denver to Omaha

Denver to Kansas City

Denver to Bismarck

Denver to Salt Lake City

Indianapolis to Orlando

Kansas City to Denver

Nashville to Orlando

New Orleans to Orlando

Omaha to Denver

Orlando to New Orleans

Orlando to Indianapolis

Orlando to Nashville,

Orlando to Pittsburgh

Pittsburgh to Orlando

Salt Lake City to Denver