$121 Cheap Frontier Airlines flights Seattle (SEA) to Sioux Falls (FSD)

Landing cheap one-way Frontier Airlines flights from SEA to FSD from $121 on Expedia couldn't be simpler --- just filter by "Price (lowest to highest)." Alternatively, check out our affordable round-trip fares from $223 for your next break.**These prices were available on Expedia within the past 7 days, for flights departing within the next year. Prices and availability are subject to change. Additional terms apply.

Start searching one to three months ahead of your departure date to score cheaper fares on Frontier Airlines flights from Seattle - Tacoma Intl. Airport (SEA) to Sioux Falls Regional Airport (FSD). You can save 25% by booking your domestic flight 34 to 86 days in advance versus last-minute reservations made 6 to 12 days out. You could also reduce costs by buying your fare on a Sunday, as it's 6% cheaper on average than a Monday, the most expensive day to book.* Get your timing spot on, and you can enjoy significant savings on domestic trips.*Ideal booking window recommendation is based on average round-trip ticket prices for January through November for 2024. Best day of the week to book recommendation is based on average round-trip ticket prices for January through October 2024. All data sourced from ARC's global airline sales database.

Sort your results by "Early Morning" and "Morning" to find the earliest departures from SEA to FSD. Jetting off early means you're 20% less likely to experience cancellations.**Most reliable time of the day recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.

With a rewarding loyalty program, Frontier Airlines is a popular choice for many passengers heading from SEA to FSD. Plus, as a Frontier Miles and One Key™ member booking through Expedia, you could earn OneKeyCash™* on eligible flights along with your airline miles.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.