Southwest's nationwide sale starts at $59 one way and closes September 10, with a 21 day advance purchase. That combination means a booking made on the last day cannot depart before October 1, even though the advertised travel window opens September 29. What the terms actually allow, and the order to book in.
Southwest is running a nationwide fare sale it calls the Travel s'more sale. The terms, quoted exactly as they appear on Southwest's flight deals page as of September 9, 2026:
"One-way as low as* $59 Travel s'more sale. *Book by 9/10. Travel valid 9/29/26-3/3/27. 21-day adv. purch. req'd. Restr., excl., & blkouts apply. Nonrefundable. Seats, days, and mkts lmtd. Add'l fees may apply."
That is the entire published offer. Everything below is what those four sentences actually mean when you sit down to book.
Two of those requirements pull against each other.
The sale closes on September 10. The fare requires a 21 day advance purchase. Twenty-one days after September 10 is October 1.
But the advertised travel window opens on September 29.
So if you book on the last day of the sale, the earliest you can fly is October 1, and the first two days of the window Southwest is advertising are not available to you. Book today, September 9, and your earliest departure is September 30, which still misses the opening day.
This is not a trick. It is what happens when a booking deadline and an advance purchase rule are set independently and the travel window is written to start earlier than either allows. It is worth knowing before you go hunting for a late September fare that the calendar will not sell you.
It is a floor, not a forecast. Southwest's own qualifier is "Seats, days, and mkts lmtd," which means the $59 fare exists on some routes, on some days, in some markets, in limited quantity. It is the cheapest thing in the sale, not the price of the sale.
The practical read: treat $59 as the number that gets you to open the search, then judge the fare you are actually shown against what that route normally costs you. A sale price is only a saving against a real baseline, and the baseline is the fare you would otherwise pay on your route, not the advertised floor on someone else's.
Southwest prints "Nonrefundable" in the terms. On Southwest that word has historically meant something narrower than it does at most airlines, because unused funds have gone back to the customer as travel credit rather than being forfeited outright.
We are not going to tell you which fare bucket this sale lands in or what happens to your money if you cancel, because Southwest does not say in the promotional text and we could not confirm it first-party today. Before you book something you are not certain about, open the fare rules on the booking page for the exact fare you are being sold and read the cancellation line there. That takes about thirty seconds and it is the only version of the answer that applies to your booking.
The sale is a cash fare promotion. The larger prize on Southwest has always been the Companion Pass, which lets a designated companion fly with you for taxes and fees on both cash and award bookings.
If you hold a Companion Pass, a cheap base fare is worth roughly double what it looks like, because the second seat costs you almost nothing on top. That turns a $59 one way into two people moving for close to $59 plus the companion's taxes. If you are working toward the Pass, a sale fare is a cheap way to add qualifying points, though the fare itself earns on what you paid, so cheap fares earn proportionally less.
We keep the earning and qualification details on our Southwest card pages, where each card's figures are checked against the issuer rather than against a promotion banner.
We did not verify how many points the same seat costs, because Southwest does not publish a points price for a sale fare in the promotional material and we could not confirm the mechanism first-party today. If you are deciding between cash and points, price the identical itinerary both ways in the same session on southwest.com and take whichever is better on your route. That comparison takes a minute and it beats any rule of thumb, including ours.
Sale terms quoted from southwest.com/special-offers/flight-deals/ on September 9, 2026. The advance purchase arithmetic is ours, calculated from Southwest's own published book-by date and 21 day requirement. Not affiliated with Southwest Airlines.