Well, travelers, this is one of those times.
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The company launched its 72-hour sale Tuesday morning, which means you only have until Thursday, June 6 to book a ticket.
A one-way fare starts at $49. They go up to around $79, $99 or $129 for longer flights.
The promotion is good for domestic travel from Aug. 20, 2019 - Dec. 18, 2019.
The dates vary for travel to and from San Juan, Puerto Rico and to international travel destinations.
Hawaii is also in the mix, with tickets for inter-island travel valid between Sept. 3 - Nov. 2, 2019.
Earlier this year, Southwest launched its sale of flights to Hawaii shortly after completing a test flight, which appeared to spark some fare wars in the friendly skies with other airlines.
Domestic travel isn't valid on Fridays and Sundays. The fares also only apply to nonstop flights.
As always, check the Southwest Airlines website for specific restrictions and dates on international travel before you book.