Starting Tuesday, travelers can book one-way flights to destinations like Belize, the Dominican Republic and the Cayman Islands for as low as $59.
Sample fares from Chicago's Midway Airport include $195 for a one-way ticket to Cabo San Lucas and $159 for a one-way ticket to Cancun.
The cheap flights are for October and November, but you'll have to act fast - the sale only lasts through September 20.
Keep in mind that booking for flights during this promotion is nonrefundable. But if your travel is a sure thing, you might want to go for it.
Check the Southwest Airlines website for specific restrictions.