Cheap flights from San Diego to St. Louis from $66

In general, September is the cheapest month to fly from San Diego to St. Louis. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $271. The month of August is another great option to travel to St. Louis, with average flight prices from San Diego averaging around $357.

The cheapest day to depart on your flight to St. Louis is on a Thursday when prices can be found for as low as $414. This is often the case because there is less demand to fly during this day of the week. If your travel schedule is flexible, try to avoid departing on a Monday because tickets tend to average around $616. These prices are subject to change though, so be sure to set up a Price Alert for flights to St. Louis.

Flying to St. Louis from San Diego in the afternoon is the least expensive time of day to depart. momondo users have found prices as low as $429 when looking at flights departing in the afternoon. In the morning is when there is more demand to fly to St. Louis, so prices are often more expensive at around $481 per ticket.

Fly from San Diego to Lambert-St Louis for the best San Diego - Lambert-St Louis flight prices

You are more likely to see cheaper flights to St. Louis from San Diego when booking weeks ahead of your departure date. In general, you can expect to find flights to St. Louis for around $394 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to St. Louis from San Diego for as low as $296 on momondo.

There is only 1 cabin class available to choose from on San Diego to Lambert-St Louis flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

You could potentially save up to 25% on your flight if you consider stops on a San Diego to St. Louis flight.

As of February 2026, prices for San Diego to St. Louis flights are approximately 22% more expensive when compared to flights at the same time last year.

Frontier is the most popular carrier operating from San Diego to Lambert-St Louis

Southwest, American Airlines and Frontier are the top three most popular airlines that fly to St. Louis from San Diego according to our data. Southwest is the first choice among our users, with 42% of people opting to fly with this airline when traveling to St. Louis. Keep in mind that there are 5 different airlines that fly to St. Louis on a routine basis, so you have a few additional options to choose from.

Phoenix (PHX) was the most common stop: 55% of momondo users choosing 1-stop flights on this route connected there.

Flights via Denver (DEN) offer the lowest average round-trip price of $302.

Flights connecting via Phoenix (PHX) have the shortest average one-way travel time: 5h 10m.

Phoenix (PHX) has the shortest average layover time for this route: 0h 50m.

The number of flights available between San Diego and St. Louis is 1 per day as of February 2026. The most frequent departure time is 12:00PM, with 66% of daily flights leaving in the afternoon.

As of February 2026, there are 9 flights per week flying from San Diego to St. Louis. The most common day of the week flights depart is Mon, with 33% of flights taking off on this day.