First, the deal. Southwest has sprung a sale. You must purchase before Friday and travel is good June 1-Oct. 5, with blackout dates of June 30, July 2, Sept. 1 and 5. There is a 14-day advance purchase requirement and best prices apply every day except Fridays and Sundays. Here's the fine print.
Now a few words about sales. I used to include a series of caveats about discounted fares in every blog I wrote about deals but stopped because it began to seem redundant. But based on comments we've been getting lately it seems that we might need to repeat them periodically.
When an airline puts seats on sale, it doesn't necessarily mean that you can't get a better price for your destination. A lot depends on what the competition is like on various specific routes and whether the route you want is a key one for the carrier holding the sale. When a airline does launch a sale, competitors often will try to match, at least.
So what should you do if you happen to be in the market for a flight? When a sale is announced, go check out the fare but also look around. For starters, just to get a sense of the competitive environment, get on a fare aggregator like kayak and plug in your dates and compare (but don't assume what you're looking at is definitive; aggregators don't necessarily have prices from all the airlines -- kayak, for instance, is blocked from Southwest's schedule). Also move your travel times and dates around --- it's usually cheapest to fly midweek and Saturdays.
Remember, airlines launch sales to ensure that a good base of seats are filled. They very, very, very seldom, if ever, discount all seats on all flights to all destinations. That means sale seats are limited. So, it's possible that you may not be able to get a seat at an advertised rate on your planned day of travel; but if a competitor is trying to match sale fares you might be able to snag a better deal elsewhere. Or if your route is one that a competitor values highly -- and offers many flights to --- and doesn't want to get beat .... you get the drift.
Bottom line: Always shop around. But also consider that it is getting tougher to get great deals. So if you know you are going to travel and you see a good fare jump on it.