Southwest Airlines offering cheap flights with tickets starting at $49

( (Southwest Airlines) )

The 72-hour flash sale is back at Southwest Airlines, with some round-trip tickets as low as $100.

Southwest Airlines holds the three-day sale twice a year. The latest iteration launched Tuesday morning.

One-way fares start at $49 and go up to $129 for longer flights.

The sale is ideal for domestic travel between August and December this year. Travel is excluded on Fridays and Sundays.

For international travel destinations and Puerto Rico, the dates vary.

If you're ready to get out of town, you have until Thursday to book and get a deal.