Discount airlines have launched time-limited sales with one-way fares as low as $25 to get U.S. customers back into the traveling mood.

Southwest Airlines said one-way tickets on routes up to 375 miles would cost $25 for flights on specific dates -- Dec 2-16 and Jan. 5-Feb. 20, USA Today reported Tuesday.

Sale prices go up incrementally: $50 for one-way tickets on trips of less than 550 miles and $75 on routes of less than 1,000 miles. For routes 1,000 or more miles the sale price, which ends Thursday, is $100.

AirTran has one-way sale prices of $39 on short routes in an offer that ends Nov. 10.

JetBlue and Frontier Airlines are matching sale prices on competitive routes.

In general, however, fares are expected to rise, Tom Parsons at BestFares.com said.

With oil prices rising, "airlines can't just keep on losing money forever," he said.

"But I still expect there to be significant fare sales like these periodically, at least through next May," he said.