The low-cost carrier on Thursday said it will reduce an average of 27 flights a day from Sept. 7 through Oct. 6 and cut 162 flights a day from Oct. 7 through Nov. 5.
It plans to adjust flight schedules in November and December as well, but said it would protect holiday bookings.
"We're confident these adjustments will create a more reliable travel experience," Southwest Airlines CEO Gary Kelly said in a statement.
The cuts are on top of its recent reductions in response to slower bookings and increased cancellations due to the spread of the Delta variant of the coronavirus.
Southwest had added more flights to its schedule to capitalize on a recovery in air travel and gain market share. However, like most in the sector, it has struggled to keep up, grappling with staff shortages.
Both American Airlines and Southwest had to cancel summer flights due to the crunch, bad weather and less network flexibility. Now they are recalling crews and resuming hiring.
The Dallas-based airline said it was "aggressively" hiring.
To deal with staff crunch, Southwest is recalling employees, who are on voluntary leave. The company expects to have all of those employees back by the end of the year.
(Reporting by Rajesh Kumar Singh; Editing by Himani Sarkar)