Cheap flights from Seattle to St. Louis from $109

In general, January is the cheapest month to fly from Seattle to St. Louis. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $237. The month of February is another great option to travel to St. Louis, with average flight prices from Seattle averaging around $287.

The cheapest day to depart on your flight to St. Louis is on a Tuesday when prices can be found for as low as $383. 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 Sunday because tickets tend to average around $627. 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 Seattle in the morning is the least expensive time of day to depart. momondo users have found prices as low as $456 when looking at flights departing in the morning. At noon is when there is more demand to fly to St. Louis, so prices are often more expensive at around $532 per ticket.

Fly from Seattle/Tacoma Intl to Lambert-St Louis for the best Seattle/Tacoma Intl - Lambert-St Louis flight prices

You are more likely to see cheaper flights to St. Louis from Seattle when booking weeks ahead of your departure date. In general, you can expect to find flights to St. Louis for around $411 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to St. Louis from Seattle for as low as $253 on momondo.

There are 4 cabin classes available to choose from on Seattle to 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 32% on your flight if you consider stops on a Seattle to St. Louis flight.

As of August 2026, prices for Seattle to St. Louis flights are approximately 2% more expensive when compared to flights at the same time last year.

Delta and Southwest are the most popular carriers operating from Seattle/Tacoma Intl to Lambert-St Louis

Alaska Airlines, Southwest and American Airlines are the top three most popular airlines that fly to St. Louis from Seattle according to our data. Alaska Airlines is the first choice among our users, with 76% of people opting to fly with this airline when traveling to St. Louis. Keep in mind that there are 7 different airlines that fly to St. Louis on a routine basis, so you have a few additional options to choose from.

Denver (DEN) was the most common stop: 60% of momondo users choosing 1-stop flights on this route connected there.

Flights via Denver (DEN) offer the lowest average round-trip price of $314.

Flights connecting via Salt Lake City (SLC) have the shortest average one-way travel time: 5h 42m.

Salt Lake City (SLC) has the shortest average layover time for this route: 0h 41m.

As of August 2026, 6 flights take off from Seattle and land in St. Louis each day. The most common flight departure time for this route is 6:00PM, with 42% of daily flights taking off in the afternoon.

43 flights are operational weekly from Seattle to St. Louis as of August 2026. The most popular departure day for this route is Thu, with 26% of flights per week taking off on this day.