$105 Cheap Frontier Airlines flights St. Louis (STL) to San Diego (SAN)

Finding cheap one-way Frontier Airlines flights from STL to SAN from $105 on Expedia couldn’t be simpler — just filter by “Price (lowest to highest).” Alternatively, check out our budget-friendly round-trip fares from $210 for your next exciting adventure.**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.

January is one of the cheapest months to travel to San Diego with Frontier Airlines. You could also find great deals on one-way and round-trip fares in November.

For cheap Frontier Airlines fares from Lambert-St. Louis Intl. Airport (STL) 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 impact how much you pay. Sunday is typically the cheapest, while Monday is often the most expensive for domestic flights. You can save 6% on average by booking your journey 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.

To figure out if there’s a direct route from STL to SAN with Frontier Airlines or another airline, select the “Nonstop” filter when looking for tickets.

Search Frontier Airlines’s earliest flights from STL to SAN by checking the “Early Morning” and “Morning” filters. Not only will you get to your destination sooner, early departures are also 20% less likely to be canceled.**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.

San Diego Intl. Airport (SAN) is the main San Diego gateway for Frontier Airlines flights from Lambert-St. Louis Intl. Airport (STL).

Offering a rewarding loyalty program, Frontier Airlines is a favorite of many travelers flying from STL to SAN. Plus, as a Frontier Miles 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.

In most cases, you can modify or cancel your flight, although additional charges may apply if you made your booking more than 24 hours ago. Want to keep your options open? Use our “Changes included” or “No cancel fee” filter to find flights that won’t charge extra if you need to adjust your plans. To make modifications, visit “Trips,” select your flight and click on “Manage Booking” for more information.