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

View $90 flight on Sun, Aug 31, 2025Opens in a new window

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Find available prices by choosing your travel dates.

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

Prices were available within the past 7 days and start at $90 for one-way flights and $179 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Southwest Airlines
Tue, Jun 10 - Tue, Jun 17
STL
St. Louis
SEA
Seattle
$179 Roundtrip, found 1 day ago
$179
Roundtrip
found 1 day ago
Select Southwest Airlines flight, departing Tue, Jun 10 from St. Louis to Seattle, returning Tue, Jun 17, priced at $179 found 1 day ago
United
Sun, Aug 31 - Thu, Sep 4
STL
St. Louis
SEA
Seattle
$180 Roundtrip, found 9 hours ago
$180
Roundtrip
found 9 hours ago
Select United flight, departing Sun, Aug 31 from St. Louis to Seattle, returning Thu, Sep 4, priced at $180 found 9 hours ago
Delta
Fri, Aug 22 - Sat, Aug 30
STL
St. Louis
SEA
Seattle
$186 Roundtrip, found 9 hours ago
$186
Roundtrip
found 9 hours ago
Select Delta flight, departing Fri, Aug 22 from St. Louis to Seattle, returning Sat, Aug 30, priced at $186 found 9 hours ago
United
Sun, Aug 31 - Tue, Sep 30
STL
St. Louis
SEA
Seattle
$187 Roundtrip, just found
$187
Roundtrip
just found
Select United flight, departing Sun, Aug 31 from St. Louis to Seattle, returning Tue, Sep 30, priced at $187 just found
Southwest Airlines
Fri, Jun 6 - Tue, Jun 10
STL
St. Louis
SEA
Seattle
$189 Roundtrip, just found
$189
Roundtrip
just found
Select Southwest Airlines flight, departing Fri, Jun 6 from St. Louis to Seattle, returning Tue, Jun 10, priced at $189 just found
American Airlines
Sun, Aug 31 - Tue, Sep 30
STL
St. Louis
SEA
Seattle
$189 Roundtrip, just found
$189
Roundtrip
just found
Select American Airlines flight, departing Sun, Aug 31 from St. Louis to Seattle, returning Tue, Sep 30, priced at $189 just found
Delta
Sun, Aug 31 - Tue, Sep 30
STL
St. Louis
SEA
Seattle
$189 Roundtrip, just found
$189
Roundtrip
just found
Select Delta flight, departing Sun, Aug 31 from St. Louis to Seattle, returning Tue, Sep 30, priced at $189 just found
Southwest Airlines
Sat, Nov 1 - Wed, Nov 5
STL
St. Louis
SEA
Seattle
$190 Roundtrip, found 2 days ago
$190
Roundtrip
found 2 days ago
Select Southwest Airlines flight, departing Sat, Nov 1 from St. Louis to Seattle, returning Wed, Nov 5, priced at $190 found 2 days ago
Delta
Fri, Aug 22 - Mon, Aug 25
STL
St. Louis
SEA
Seattle
$190 Roundtrip, found 7 hours ago
$190
Roundtrip
found 7 hours ago
Select Delta flight, departing Fri, Aug 22 from St. Louis to Seattle, returning Mon, Aug 25, priced at $190 found 7 hours ago
Frontier Airlines
Sat, May 31 - Thu, Jun 5
STL
St. Louis
SEA
Seattle
$198 Roundtrip, found 11 hours ago
$198
Roundtrip
found 11 hours ago
Select Frontier Airlines flight, departing Sat, May 31 from St. Louis to Seattle, returning Thu, Jun 5, priced at $198 found 11 hours ago
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
$179
Distance
1705 mi

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 June. 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 $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 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?
Book cheap return flights starting from $237 from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA). 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 Alaska Airlines flight leaving STL on May 13 2025 and touching down at SEA. The price was last updated on April 24 2025 and has not changed since.
What is the cheapest month to fly from STL to SEA?
The cheapest flights from STL to SEA are usually during off-peak season, when demand is lower. To save money, avoid flying during public holidays, school breaks and major local events.
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 STL to SEA?
With tickets starting at $119 for a one-way flight from STL to SEA, Alaska Airlines is currently the cheapest carrier flying this route. This fare is based on the lowest price found on Expedia departing within the next three months. The flight takes off from STL on June 17 2025. Prices were last updated on April 24 2025 and have not changed since.
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.