$90 Cheap Flights from Seattle (SEA) to St. Louis (STL)

View $90 flight on Tue, Sep 23, 2025Opens in a new window

Popular airlines from Seattle-Tacoma International Airport (SEA) to St. Louis Lambert Intl. Airport (STL)

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Cheap Flights from Seattle to St. Louis (SEA-STL)

Prices were available within the past 7 days and start at $90 for one-way flights and $180 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

United
Tue, Sep 16 - Sat, Sep 20
SEA
Seattle
STL
St. Louis
$180 Roundtrip, just found
$180
Roundtrip
just found
Select United flight, departing Tue, Sep 16 from Seattle to St. Louis, returning Sat, Sep 20, priced at $180 just found
American Airlines
Fri, Oct 3 - Mon, Oct 6
SEA
Seattle
STL
St. Louis
$189 Roundtrip, just found
$189
Roundtrip
just found
Select American Airlines flight, departing Fri, Oct 3 from Seattle to St. Louis, returning Mon, Oct 6, priced at $189 just found
United
Sat, Sep 20 - Wed, Sep 24
SEA
Seattle
STL
St. Louis
$194 Roundtrip, just found
$194
Roundtrip
just found
Select United flight, departing Sat, Sep 20 from Seattle to St. Louis, returning Wed, Sep 24, priced at $194 just found
United
Wed, Sep 3 - Thu, Sep 4
SEA
Seattle
STL
St. Louis
$195 Roundtrip, found 6 hours ago
$195
Roundtrip
found 6 hours ago
Select United flight, departing Wed, Sep 3 from Seattle to St. Louis, returning Thu, Sep 4, priced at $195 found 6 hours ago
United
Tue, Sep 23 - Sat, Sep 27
SEA
Seattle
STL
St. Louis
$198 Roundtrip, just found
$198
Roundtrip
just found
Select United flight, departing Tue, Sep 23 from Seattle to St. Louis, returning Sat, Sep 27, priced at $198 just found
Frontier Airlines
Fri, Aug 15 - Tue, Aug 19
SEA
Seattle
STL
St. Louis
$199 Roundtrip, just found
$199
Roundtrip
just found
Select Frontier Airlines flight, departing Fri, Aug 15 from Seattle to St. Louis, returning Tue, Aug 19, priced at $199 just found
American Airlines
Wed, Oct 8 - Wed, Oct 15
SEA
Seattle
STL
St. Louis
$203 Roundtrip, found 9 hours ago
$203
Roundtrip
found 9 hours ago
Select American Airlines flight, departing Wed, Oct 8 from Seattle to St. Louis, returning Wed, Oct 15, priced at $203 found 9 hours ago
United
Thu, Aug 21 - Sat, Aug 30
SEA
Seattle
STL
St. Louis
$204 Roundtrip, found 14 hours ago
$204
Roundtrip
found 14 hours ago
Select United flight, departing Thu, Aug 21 from Seattle to St. Louis, returning Sat, Aug 30, priced at $204 found 14 hours ago
Southwest Airlines
Thu, Aug 21 - Mon, Aug 25
SEA
Seattle
STL
St. Louis
$216 Roundtrip, just found
$216
Roundtrip
just found
Select Southwest Airlines flight, departing Thu, Aug 21 from Seattle to St. Louis, returning Mon, Aug 25, priced at $216 just found
Alaska Airlines
Tue, Sep 2 - Sat, Sep 6
SEA
Seattle
STL
St. Louis
$220 Roundtrip, just found
$220
Roundtrip
just found
Select Alaska Airlines flight, departing Tue, Sep 2 from Seattle to St. Louis, returning Sat, Sep 6, priced at $220 just found

Find the cheapest month to fly from Seattle (SEA) to St. Louis (STL)

August is typically the cheapest month to fly

From $133 - $237 per traveler.

Graph displaying average flight prices per month

Flights from Seattle (SEA) to St. Louis (STL)
Origin airport
Seattle - Tacoma Intl.
Destination airport
Lambert-St. Louis Intl.
Airlines serving
Alaska Airlines, American Airlines, Delta, Frontier Airlines, Southwest Airlines, Sun Country Airlines, United
Roundtrip price
$179
Distance
1705 mi
Average flight time
6 hours 42 mins

Seattle to St. Louis Flights

The cheapest times to fly from Seattle to St. Louis

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from Seattle to St. Louis are during the month of September. You can find some of the cheapest flights from Seattle to St. Louis with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from Seattle to St. Louis

Sunday is one of the best days to book for cheap flights from Seattle to St. Louis: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

 

How to find cheap round-trip tickets from Seattle to St. Louis

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from Seattle to St. Louis in 2025. You can also book with separate airlines for your outbound and return journeys, from $90 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

 

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap Seattle to St. Louis flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

 

You could also save big by booking one of Expedia's vacation packages. Bundling together your Seattle to St. Louis airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

 

*Terms apply.

 

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

 

Frequently asked questions

How much does a flight from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL) cost?
Book cheap return fares starting from $223 from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL). This information is based on the cheapest price found on Expedia for this return journey departing within the next three months. This airfare is for a Southwest Airlines flight leaving SEA on July 16 2025 and touching down at STL. The price was last updated on June 25 2025 and has not changed since.
What is the cheapest month to fly from SEA to STL?
To snag a cheap fare, check for direct flights from SEA to STL taking off in November. You can find a one-way Alaska Airlines flight for $119 leaving on November 27 2025. This price is based on the cheapest direct flight found on Expedia for this route in the next 330 days. The price was last updated on June 25 2025 and remains unchanged.
Which airlines fly direct from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL)?
Hop on a nonstop flight with Alaska Airlines and head straight from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL).
What is the cheapest airline that flies from SEA to STL?
Take off from SEA to STL with Alaska Airlines. This airline currently offers the lowest one-way fare on this route, starting at $119. This fare is based on the lowest price found on Expedia departing within the next three months. The flight takes off from SEA on August 31 2025. Prices were last updated on June 25 2025 and have not changed since.
How many flights per day from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL)?
On average, just 1 nonstop flight departs each day from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL). Looking for more options? Use our filter tool to find flights with layovers and squeeze in a visit to another city along the way.
What are the most popular departure times for flights from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL)?
More people fly between SEA and STL at 8 AM than at any other point in the day. Prefer a quieter experience? Travel outside of rush hours and it's possible you'll save on your fare as well.
What day of the week has the most flights from SEA to STL?
If you depart on a Friday, you'll get the largest range of choices for flights from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL).
What is the earliest flight from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL)?
Seattle - Tacoma Intl. Airport (SEA)'s earliest flight to Lambert-St. Louis Intl. Airport (STL) takes off at approximately 8:00AM UTC-8. With a flight time of 3h 53m, you'll touch down at around 1:53PM UTC-6.
How long does it take to fly from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL)?
The average flight time from SEA to STL is 3 hours and 52 minutes, covering a total distance of 1,700 mi.
What airline has the least delays from SEA to STL?
American Airlines has the best performance for on-time direct flights from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL), with an on-time rating of 98%. Use the Expedia App to look up your flight status before you jet off and receive notifications about any changes.
What is the best time to fly from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL)?
To land at Lambert-St. Louis Intl. Airport (STL) on schedule, pick a flight that leaves Seattle - Tacoma Intl. Airport (SEA) before 3 PM. The likelihood of cancellations is 22% higher, on average, for departures after this time.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
What airports do you fly into for St. Louis from Seattle - Tacoma Intl. Airport (SEA)?
If you're traveling on a direct flight from Seattle - Tacoma Intl. Airport (SEA) to St. Louis, Lambert-St. Louis Intl. Airport (STL) is the only airport you can touch down at.
Is it cheaper to buy a plane ticket from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL) last-minute?
Last-minute fares from SEA to STL are generally more expensive. To secure the lowest prices, start looking for flights well ahead of time. That said, if you can play around with your travel dates, you may land a cheap fare right before your journey.
Is it cheaper to book a SEA to STL flight and hotel package?
You can save money by booking a SEA to STL flight and hotel package compared to booking separately. In fact, you could save hundreds of dollars by bundling with Expedia. And it's simple to manage it all in one place. After selecting your ideal accommodations and flights, consider other add-ons like car rentals, tours and activities.
Can I cancel or change the date of my flight from Seattle - Tacoma Intl. Airport (SEA) to Lambert-St. Louis Intl. Airport (STL)?
In most instances, you can cancel or modify your SEA to STL flight. However, there may be additional fees, especially if you made your booking over 24 hours ago. Double-check your itinerary for the airline's rules and fees on flight changes, or if you'd like more information, visit our Customer Service portal.

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