Southwest Airlines is having a massive 72-hour sale with round-trip fares below $100

If you haven't planned a summer vacation yet, you may be in luck. Southwest Airlines' massive bi-annual fare sale is back -- and get this, some round-trip flights are below $100.

According to CNBC, "Flights begin at $49 each way on Southwest's shortest routes and increase to $79, $99 or $129 each way for longer flights." The reduced prices are valid on domestic travel between August 22 through December 13, 2017 (okay, so it'd be more like an end-of-summer or fall vacay) and only apply to nonstop flights.

RELATED: TripAdvisor names the top hotels in the world

The major announcement, however, is seemingly not without its fair share of catches. "Those used to Southwest's previous sale fares should be warned that the availability of Southwest's cheapest fares appears to be somewhat more limited than in past sales," USA Today claims. You don't know until you try though, right?

The sale ends on Thursday, June 8 at 11:59 p.m. in the respective time zone of the originating city. For all exclusions and exceptions, see the full details here.

RELATED: A ranking of America's top 10 airlines