Frontier Airlines is launching nine new routes in August.

The Denver-based ultra-low-cost carrier is holding a two-day fare sale in conjunction with the launch of the new routes.

It includes one-way tickets for as little as $29.

The sale ends at 11:59 p.m. ET on Wednesday.

On Tuesday, Frontier Airlines announced the addition of nine new routes to destinations across the US. The Denver-based ultra-low-cost carrier will also expand to Norfolk, Virginia, and Wichita, Kansas.

The new routes, including six out of Jacksonville, Florida, will launch in the middle of August, Frontier said.

"These additional nine routes are the latest evidence of Frontier's commitment to making air travel more affordable and accessible to everyone," the airline's senior vice president of commercial, Daniel Shurz, said in a statement. "We're offering not only amazing low fares but a reliable and friendly service that allows customers to customize their travel experience to their needs and budget."

Shurz added: "This empowers more people than ever to fly. This is what our Low Fares Done Right philosophy is all about."

The new routes include service between:

Denver and Norfolk

Denver and Wichita

Jacksonville and Buffalo, New York

Jacksonville and Kansas City, Missouri

Jacksonville and Las Vegas

Jacksonville and Milwaukee

Jacksonville and Minneapolis

Jacksonville and St. Louis

Norfolk and Orlando, Florida

To commemorate the launch of these new routes, Frontier is holding a two-day sale with tickets as low as $29 one-way between Denver and Wichita, making a round trip $58. Flights between Jacksonville and St. Louis, as well as between Orlando and Norfolk, are on sale for $39 each way.

All sale tickets must be purchased by 11:59 p.m. ET on Wednesday and are valid for travel between August 12 and November 14.

As with all sales, there is some serious fine print associated with these cheap tickets.

The fares are generally valid for travel on Tuesdays and Wednesdays. The sale covers flights from Florida from Tuesday to Friday and those to Florida from Sunday to Wednesday.

For flights out of Denver, sale prices are valid for travel on Tuesdays, Wednesdays, Thursdays, and Saturdays. Discounted fares into Denver are available on flights on Mondays, Tuesdays, Wednesdays, and Saturdays.

On the bright side, the fares are one-way and do not require a round-trip booking.

Despite its cheap flights and fast growth, Frontier has struggled with consumer satisfaction. It was rated the second-worst airline in the US in the latest Consumer Reports rankings. The airline also finished second to last in the latest report published by the American Consumer Satisfaction Index.