This morning both JetBlue and Southwest launched fall fare sales, with slightly different terms.
To get the JetBlue discounts you must purchase before Sept. 8 for travel between Sept. 13 and Dec. 15, any day except Friday and Sunday. Seven-day advance purchase may be required and there are blackout dates. Here is the fine print.
For Southwest, you need to buy before Sept. 9 for travel through Dec. 14, with 10-day advance purchase required. Special prices are good on Tuesdays, Wednesdays, and Saturdays. Here is the fine print.
The prices look pretty good but it will pay to shop around as I would expect competitor airlines will try to match fares on selected routes.