The deal is good for travel between Sept. 1 and Nov. 20, 2015.
A flight from Chicago to San Juan, Puerto Rico, is going for $144, but you must book your trip by Wednesday.
The sale does include some blackout dates.
Full list of Deals
The sale comes a month after JetBlue stopped offering free checked bags. Starting June 30, JetBlue began charging $25 per checked bag. Previously the budget airline allowed passengers to check one bag for free.
Southwest is now the only remaining airline that doesn't charge baggage fees.
The airline isn't new to rock-bottom deals. In 2010, to celebrate its 10th anniversary, the airline offered $10 last-minute tickets.