Frontier Airlines offering $20 flights today only

Courtesy of Frontier Airlines

In celebration of their birthday, Frontier Airlines is offering flights as low as $20 -- but you have to book by July 6.

The flights are for travel on select days between August 15 and October 4 to select markets. The cheapest flight out of Houston starts at $20 one way to Atlanta. Seats for flights from Houston to Denver start at $49 one way. And flights from Houston to Las Vegas, Cleveland, and Cincinnati start at $49 one way. 

Seats on flights are limited and other restrictions may apply. To find a full list of available flights, click here. Additional fees for luggage and seating preferences also apply.