$84 Cheap Flights from St. Louis (STL) to Seattle (SEA)

View $84 flight on Sat, Sep 6, 2025Opens in a new window

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

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Today's featured flight deals from St. Louis Lambert Intl. Airport (STL) to Seattle-Tacoma International Airport (SEA)

Nonstop
Carry-on included
Lower price than typical

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

Prices were available within the past 7 days and start at $84 for one-way flights and $168 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

United
Sat, Sep 20 - Tue, Sep 30
STL
St. Louis
SEA
Seattle
$168 Roundtrip, just found
$168
Roundtrip
just found
Select United flight, departing Sat, Sep 20 from St. Louis to Seattle, returning Tue, Sep 30, priced at $168 just found
Delta
Sat, Nov 8 - Tue, Nov 18
STL
St. Louis
SEA
Seattle
$174 Roundtrip, just found
$174
Roundtrip
just found
Select Delta flight, departing Sat, Nov 8 from St. Louis to Seattle, returning Tue, Nov 18, priced at $174 just found
United
Wed, Sep 3 - Wed, Sep 10
STL
St. Louis
SEA
Seattle
$175 Roundtrip, just found
$175
Roundtrip
just found
Select United flight, departing Wed, Sep 3 from St. Louis to Seattle, returning Wed, Sep 10, priced at $175 just found
American Airlines
Tue, Sep 23 - Wed, Oct 1
STL
St. Louis
SEA
Seattle
$177 Roundtrip, found 2 hours ago
$177
Roundtrip
found 2 hours ago
Select American Airlines flight, departing Tue, Sep 23 from St. Louis to Seattle, returning Wed, Oct 1, priced at $177 found 2 hours ago
Delta
Tue, Oct 14 - Wed, Oct 22
STL
St. Louis
SEA
Seattle
$178 Roundtrip, found 4 hours ago
$178
Roundtrip
found 4 hours ago
Select Delta flight, departing Tue, Oct 14 from St. Louis to Seattle, returning Wed, Oct 22, priced at $178 found 4 hours ago
Delta
Wed, Sep 3 - Wed, Sep 10
STL
St. Louis
SEA
Seattle
$179 Roundtrip, just found
$179
Roundtrip
just found
Select Delta flight, departing Wed, Sep 3 from St. Louis to Seattle, returning Wed, Sep 10, priced at $179 just found
United
Tue, Sep 23 - Fri, Oct 3
STL
St. Louis
SEA
Seattle
$181 Roundtrip, just found
$181
Roundtrip
just found
Select United flight, departing Tue, Sep 23 from St. Louis to Seattle, returning Fri, Oct 3, priced at $181 just found
Delta
Wed, Sep 24 - Mon, Sep 29
STL
St. Louis
SEA
Seattle
$183 Roundtrip, just found
$183
Roundtrip
just found
Select Delta flight, departing Wed, Sep 24 from St. Louis to Seattle, returning Mon, Sep 29, priced at $183 just found
Frontier Airlines
Mon, Sep 22 - Mon, Oct 13
STL
St. Louis
SEA
Seattle
$239 Roundtrip, found 3 days ago
$239
Roundtrip
found 3 days ago
Select Frontier Airlines flight, departing Mon, Sep 22 from St. Louis to Seattle, returning Mon, Oct 13, priced at $239 found 3 days ago
Southwest Airlines
Mon, Sep 15 - Thu, Sep 25
STL
St. Louis
SEA
Seattle
$249 Roundtrip, just found
$249
Roundtrip
just found
Select Southwest Airlines flight, departing Mon, Sep 15 from St. Louis to Seattle, returning Thu, Sep 25, priced at $249 just found

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

October is typically the cheapest month to fly

From $138 - $216 per traveler.

Graph displaying average flight prices per month

Alternative airports near Seattle

Prices were available within the past 7 days. Prices and availability are subject to change.

Select flight to Seattle - Tacoma Intl. SEA. Cheapest option available. Average driving time to city center is 20 minutes. Flights from $203
SEA
Seattle - Tacoma Intl.
Cheapest
Average driving time to city center20 min
Flights from $203
Flights from St. Louis (STL) to Seattle (SEA)
Origin airport
Lambert-St. Louis Intl.
Destination airport
Seattle - Tacoma Intl.
Airlines serving
Alaska Airlines, American Airlines, Delta, Frontier Airlines, Southwest Airlines, Sun Country Airlines, United
Roundtrip price
$167
Distance
1705 mi
Average flight time
3 hours 41 mins

St. Louis to Seattle Flights

The cheapest times to fly from St. Louis to Seattle

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 St. Louis to Seattle are during the month of September. You can find some of the cheapest flights from St. Louis to Seattle with Expedia's search tool and vast selection of airlines.

 

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

Sunday is one of the best days to book for cheap flights from St. Louis to Seattle: 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 St. Louis to Seattle

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 St. Louis to Seattle in 2025. You can also book with separate airlines for your outbound and return journeys, from $84 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 St. Louis to Seattle 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 St. Louis to Seattle 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 Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA) cost?
Grab a cheap one-way flight from $84 or cheap return flight from $168 from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to find our cheapest flight offers on this route.
What is the cheapest month to fly from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA)?
The cheapest month to fly from STL to SEA is September, when demand is low. Off-peak season is generally when airlines offer lower prices between these airports.
Which airlines fly direct from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA)?
You can travel nonstop from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA) on an Alaska Airlines flight.
What is the cheapest airline that flies from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA)?
Use the filter tool on Expedia to compare airlines and find the most affordable carrier that'll take you from STL to SEA. Then, sort your results by "Price (lowest to highest)" to snap up a good deal.
How many flights per day from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA)?
On average, there's only 1 direct flight departing from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA) every day. If this doesn't fit your plans, think about flights with layovers. Simply filter your search on Expedia to include one stop or more to find a better alternative.
What are the most popular departure times for flights from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA)?
Flights between STL and SEA tend to be busiest at 2 PM. If you'd like a more relaxed atmosphere and possibly cheaper tickets, look for a departure outside the usual busy windows.
What day of the week has the most flights from STL to SEA?
Sunday offers the most flights from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA). Consider leaving on this day and you'll have the best chance of finding a departure that works with your plans.
What is the earliest flight from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA)?
Catch the earliest flight at around 7:00AM UTC-6, heading out of Lambert-St. Louis Intl. Airport (STL). You'll be in the air for around 4h 42m, reaching Seattle - Tacoma Intl. Airport (SEA) at approximately 9:42AM UTC-8.
How long does it take to fly from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA)?
It takes around 4 hours and 41 minutes to travel the 1,700 mi from STL to SEA.
What is the best time to fly from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA)?
To avoid possible delays on the Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA) route, travel before 3 PM. Flights after this time have a 22% higher chance of being canceled.**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 Seattle from Lambert-St. Louis Intl. Airport (STL)?
If you're taking a direct flight from Lambert-St. Louis Intl. Airport (STL) to Seattle, Seattle - Tacoma Intl. Airport (SEA) is the only airport you can touch down at.
Is it cheaper to buy a plane ticket from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA) last-minute?
Holding off until just before your trip to book your flight from STL to SEA often results in higher prices. While you might find some last-minute deals, they're not always guaranteed. Be flexible with your travel plans for the best chance of scoring a bargain.
Is it cheaper to book a STL to SEA flight and hotel package?
Compared with arranging flights and hotels separately, booking a STL to SEA flight and hotel package with Expedia could result in significant savings. Better yet, having everything in one convenient place will take the hassle out of travel planning. Just pick your flights and choose from our wide range of hotels, then personalize your trip with other add-ons like tours, activities and car rentals.
Can I cancel or change the date of my flight from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA)?
Usually, it's possible to reschedule or cancel your STL to SEA flight. However, if the booking was made more than 24 hours ago, additional charges may apply. Check your airline's policies in your itinerary to see what changes are allowed and whether any costs are involved. You'll also find further details on our Customer Service portal.

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*Available to One Key members.