Southwest periodically make flights for further in the future available. Starting now they’ll be adding flights until March 8th, 2017. When I asked exactly when these flights would be added, I received this response from their Twitter team.
@Drofcredit Hey there! We will begin loading schedules at midnight and continue to load throughout the day. ^AB
— Southwest Airlines (@SouthwestAir) July 7, 2016
Southwest has a pretty good cancellation/refunds policy, depending on the fare you’ve booked you’ll either receive a points refund (Wanna Get Away) or cash refund (Business Select or Anytime – returned to credit card if you used one). That means it’s often best to book flights as soon as they become available and periodically check to see if the price has decreased, if it has you can cancel and rebook.
Not sure how helpful this is to readers, let me know in comments if you want to know when airline availability becomes released or not. Also it might be worth checking later in the day as more flights are added. Update: Seems like they’ve made the schedule available until March 8th, 2017 instead of the 7th.