Cheap flights from St. Louis to Seattle from $75

In general, February is the cheapest month to fly from St. Louis to Seattle. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $237. If you don’t want to visit Seattle in February, then you should wait until March to fly from St. Louis, when ticket prices are also cheap, with an average price of $289.

On average, the least expensive day to fly to Seattle from St. Louis is on a Friday. momondo users have found tickets for Friday departures for as low as $481. However, this price may fluctuate depending on the airline, the season, and holidays. On the other hand, Monday is the most expensive day to depart from St. Louis because it is more convenient for both business and leisure travelers. As a result, prices tend to be around $548.

Flying to Seattle from St. Louis in the evening is the least expensive time of day to depart. momondo users have found prices as low as $470 when looking at flights departing in the evening. Flights to Seattle are more costly at noon, with an average ticket price of $552. Departure times at noon fall within the peak daily travel times, which is why tickets can be more expensive.

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

You are more likely to see cheaper flights to Seattle from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to Seattle for around $373 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Seattle from St. Louis for as low as $321 on momondo.

There are 4 cabin classes available to choose from on St. Louis to Seattle 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 22% on your flight if you consider stops on a St. Louis to Seattle flight.

As of October 2026, prices for St. Louis to Seattle flights are approximately 37% cheaper when compared to flights at the same time last year.

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

Alaska Airlines, American Airlines and Southwest are the top three most popular airlines that fly to Seattle from St. Louis according to our data. Alaska Airlines is the first choice among our users, with 73% of people opting to fly with this airline when traveling to Seattle. Keep in mind that there are 6 different airlines that fly to Seattle on a routine basis, so you have a few additional options to choose from.

Chicago (ORD) was the most common stop: 43% of momondo users choosing 1-stop flights on this route connected there.

Flights via Dallas (DFW) offer the lowest average round-trip price of $158.

Flights connecting via Salt Lake City (SLC) have the shortest average one-way travel time: 7h 01m.

Phoenix (PHX) has the shortest average layover time for this route: 1h 10m.

As of October 2026, 3 flights take off from St. Louis and land in Seattle each day. The most common flight departure time for this route is 6:00AM, with 53% of daily flights taking off at noon.

The number of flights available between St. Louis and Seattle is 22 per week as of October 2026. The most frequent departure day is Wed, with 32% of weekly flights leaving on this day.