Southwest Airlines: Roundtrip St Louis to Seattle Airfares

No special codes or coupons are required. Get these Southwest Airlines round-trip airfares while available. Fares are for travel between St. Louis (STL) and Seattle (SEA), making one stop.

This deal is available for basic economy fares, which include a personal item and a carry-on bag but no free checked bag.

Travel Availability

• Departures from St. Louis (STL): September 29-30; October 1, 4, 7-8, 14-15, 18, 21-22, 25, 28-29; November 1, 4-5, 8, 11-12, 15, 18-19, 22, 25; December 2-3, 6, 9-10, 13, 17
• Departures from Seattle (SEA): September 30; October 1, 4, 7-8, 14-15, 18, 21-22, 25, 28-29; November 1, 4-5, 8, 11-12, 15, 18-19, 22; December 2-3, 6, 9-10, 13, 16

Important Exclusions

• This offer expires on December 31, 2025.