$1,604 Cheap United flights Bilbao (BIO) to San Diego (SAN)

You can discover cheap return United Airlines flights from $887 from BIO to SAN by filtering your results from "Price (lowest to highest)" on Expedia. Or search for bargains from $1,604 for a one-way trip.**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 get affordable flights from BIO to SAN with United Airlines, begin your search about one month before your intended departure. You can save 17% when you lock in your international tickets 18 to 29 days ahead instead of booking four to five months in advance. Another tip? Booking on Sunday can lead to average savings of 17% compared to Friday (the most expensive day).**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 BIO to SAN. Setting off early means you're 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.

Offering a rewarding loyalty program, United Airlines is a popular choice for many travelers flying from BIO to SAN. Plus, if you're a United Mileage Plus and One Key™ member booking through Expedia, you can earn OneKeyCash™* on eligible flights on top of your airline miles.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.