Southwest Airlines is currently offering 30% off base fares with promo code ONBOARD when you book by 2/26/26 and travel between 4/7/26 and 5/20/26. Note that Southwest promo codes are typically capacity controlled and blackout dates apply, so you’ll just have to check the flights you want to book to see whether the code applies to your dates/routes or not.

The Deal
- Southwest Airlines is offering 30% off base fares on select flights when you book using promo code ONBOARD by 2/26/26 and travel between 4/7/26 and 5/20/26. The discount only applies to select flights for continental US travel and interisland Hawaii travel.
- Direct link to this deal
Key Terms
- Use code ONBOARD by 2/26 for travel on select flights between 4/7-5/20.
- Continental U.S. and interisland HI travel only.
- Retrictions and exclusions apply
- Seats/days/markets limited
- Discount applied pre-government taxes/fees.
Quick Thoughts
Southwest promos like this always depend on the stars aligning as they don’t tend to apply to all flights and markets during the travel period. Still, if you have plans to travel during the window, it is worth checking the code (and double-checking previously-booked flights to see if you can rebook and save).





FWIW, over the weekend I booked two flights that this offer now applies to. Both are now showing far higher fares, which are discounted 30%, but remain higher than they were over the weekend even after the discount. Not the first time I’ve (anecdotally) seen fares in one of these “sales” be higher than fares I had seen a day or two before the “sale” began.
Yeah, that happens with almost every company and certainly with airfare sales. Good to keep an eye on prices to know when you’re getting a deal.