$89 Cheap United flights Seattle (SEA) to San Diego (SAN)

Apply the "Price (lowest to highest)" filter on Expedia to search for cheap United Airlines round-trip flights from $174 from SEA to SAN. Affordable one-way fares from $89 are also on offer.**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.

To find cheap United Airlines fares from Seattle - Tacoma Intl. Airport (SEA) to San Diego Intl. Airport (SAN), start searching one to three months before your intended departure. Securing domestic flights 34 to 86 days in advance could save you 25% compared to booking just 6 to 12 days ahead. The day you book can also influence the overall cost. Sunday is typically the most affordable, while Monday is often the most expensive for domestic flights. You can save 6% on average by booking your flight on a Sunday.**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.

Filter your results by "Early Morning" and "Morning" to find the earliest departures from SEA to SAN. Leaving early means flight cancellations are less likely.**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.

A rewarding loyalty program and the ability to collect points through United Mileage Plus are the start of the reasons to depart from SEA to SAN with United Airlines. Plus, when you sign up to our One Key™ program, you can receive OneKeyCash™* in addition to United Airlines's loyalty program earnings. It's yours to spend on your next adventure.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.