$100 Cheap American Airlines flights St. Louis (STL) to San Diego (SAN)

Scoring cheap one-way American Airlines flights from STL to SAN from $100 on Expedia is easy --- just filter by "Price (lowest to highest)." Alternatively, check out our budget-friendly round-trip fares from $263 for your next getaway.**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 cheap fares on American Airlines flights from Lambert-St. Louis Intl. Airport (STL) to San Diego Intl. Airport (SAN). 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 cut costs by buying your fare on a Sunday, as it's 6% cheaper on average than a Monday, the most expensive day to book.* Nail your timing, 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 "Morning" and "Early Morning" to find the earliest departures from STL to SAN. Setting 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.