Southwest's schedule revision, which comes a day after Boeing announced a 737 production freeze, will mean roughly 300 weekday flights being removed from the airline's total peak-day schedule of more than 4,000 daily flights, it said.
Southwest spokesman Chris Mainz said the decision was already in the works as part of the airline's rolling 30-day schedule evaluation and not tied to Boeing's production halt.
Last week, American Airlines Group Inc extended its 737 MAX cancellations through April 6 after the U.S. Federal Aviation Administration said it would not approve the jets to fly again this year.
Southwest, the world's largest Boeing 737 MAX operator, had 34 MAX planes in its fleet when they were grounded worldwide in March following two crashes on Lion Air and Ethiopian Airlines that killed 346 people within five months.United Airlines, the other U.S. MAX operator, is scheduling without the plane until early March.