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$66+ Cheap flights from St. Louis to Seattle (STL - SEA)

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 11/1. Fares are subject to change and may not be available on all flights or dates of travel.
STL — SEA
Oct 25 — Nov 11
Sat 10/25
Sat 11/1
1 adult, Economy
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1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

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Cheapflights Tip: The best prices from Lambert-St Louis to Seattle/Tacoma Intl are usually found in October or November, booked 69 days in advance, depart on a Tuesday or Wednesday and return on a Thursday

Cheap flight deals from St. Louis to Seattle

Discover tips and strategies to find the most affordable flight options for your journey from St. Louis (STL) to Seattle (SEA). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated September 25, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$209
(American Airlines)

One-way from

$66
(Southwest)

Popular in

July

Cheapest in

October

Average price

$316

Good round-trip deal

$298 or less

Good one-way deal

$179 or less
Provider with most accurate pricing for Lambert-St Louis-Seattle/Tacoma Intl flight deals.
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Provider most trusted by Cheapflights users for Lambert-St Louis-Seattle/Tacoma Intl flights.
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From Lambert-St Louis to Seattle/Tacoma Intl
Search Deals
One-way flight from Lambert-St Louis to Seattle/Tacoma Intl
Search Deals
Highest demand for flights based on searches. 13% potential increase in price ($55 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($9 potential savings vs. average RT price).
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Average for round-trip flights in September 2025
Search Deals
Price to beat on a round-trip flight from Lambert-St Louis to Seattle/Tacoma Intl.
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Price to beat on a one-way flight from Lambert-St Louis to Seattle/Tacoma Intl.
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Find flight deals from St. Louis to Seattle

Cheapest flights from St. Louis to Seattle
Explore the most affordable flight options available from St. Louis to Seattle. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 25, 2025.

This Southwest deal was found by Cheapflights users on 9/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 10/197:50 pmSTL - SEA
1 stop7h 35mSouthwest
Fri 10/249:35 amSEA - STL
1 stop7h 45mSouthwest
Deal found 9/24$209
This Southwest deal was found by Cheapflights users on 9/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/274:40 pmSTL - SEA
2 stops10h 10mSouthwest
Mon 11/36:15 amSEA - STL
1 stop8h 50mSouthwest
Deal found 9/24$214
This United Airlines deal was found by Cheapflights users on 9/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/175:35 pmSTL - SEA
1 stop7h 40mUnited Airlines
Mon 10/2011:10 pmSEA - STL
1 stop8h 42mUnited Airlines
Deal found 9/24$217
This Delta deal was found by Cheapflights users on 9/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/66:00 amSTL - SEA
1 stop6h 45mDelta
Wed 11/129:30 amSEA - STL
1 stop7h 27mDelta
Deal found 9/24$218
This KAYAK deal was found by Cheapflights users on 9/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure KAYAK is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/216:33 amSTL - SEA
Nonstop4h 32mAlaska Airlines
Sat 10/256:02 pmSEA - STL
Nonstop4h 01mAlaska Airlines
Deal found 9/24$219
This Booking.com deal was found by Cheapflights users on 9/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 10/1210:17 amSTL - SEA
1 stop24h 31mFrontier
Fri 10/172:31 pmSEA - STL
1 stop16h 36mFrontier
Deal found 9/24$220
This Orbitz deal was found by Cheapflights users on 9/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/243:57 pmSTL - SEA
Nonstop4h 28mMultiple Airlines
Sun 10/268:43 pmSEA - STL
1 stop10h 24mMultiple Airlines
Deal found 9/24$221
This United Airlines deal was found by Cheapflights users on 9/25. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/215:15 amSTL - SEA
1 stop6h 44mUnited Airlines
Sat 10/255:00 amSEA - STL
2 stops8h 44mUnited Airlines
Deal found 9/25$222
This Frontier deal was found by Cheapflights users on 9/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/77:45 pmSTL - SEA
2 stops14h 33mFrontier
Thu 11/137:17 pmSEA - STL
2 stops11h 50mFrontier
Deal found 9/24$225
This CheapOair deal was found by Cheapflights users on 9/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/107:52 pmSTL - SEA
1 stop18h 15mFrontier
Tue 10/141:02 pmSEA - STL
1 stop18h 05mFrontier
Deal found 9/24$226
This CheapOair deal was found by Cheapflights users on 9/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/77:52 pmSTL - SEA
1 stop18h 15mFrontier
Sat 10/118:43 pmSEA - STL
1 stop10h 24mFrontier
Deal found 9/24$227
This Frontier deal was found by Cheapflights users on 9/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/114:33 pmSTL - SEA
2 stops17h 00mFrontier
Mon 10/138:43 pmSEA - STL
1 stop10h 24mFrontier
Deal found 9/24$229

Cheapflights Fare Finder

 
Customize your flight search to find flights from St. Louis to Seattle that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated September 25, 2025.
Use the filters below to find and compare flights from St. Louis to Seattle that are best for you.

Fly from

St. Louis

Fly to

Seattle

Route

Depart

Return

Price

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Sat 11/8

6:50 am-12:47 pm

1 stop7h 57m

Seattle/Tacoma Intl

Sun 11/9

6:00 am-5:09 pm

1 stop9h 09m

$218

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Wed 10/22

1:40 pm-5:53 pm

1 stop6h 13m

Seattle/Tacoma Intl

Sat 10/25

5:00 am-3:44 pm

2 stops8h 44m

$222

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Wed 11/5

7:00 am-9:33 am

Nonstop4h 33m

Seattle/Tacoma Intl

Sat 11/8

9:15 am-3:18 pm

Nonstop4h 03m

$237

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Sat 2/28

2:55 pm-5:21 pm

Nonstop4h 26m

Seattle/Tacoma Intl

Tue 3/3

6:00 pm-11:56 pm

Nonstop3h 56m

$237

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Sun 11/9

6:00 am-10:54 am

1 stop6h 54m

Seattle/Tacoma Intl

Thu 11/13

1:49 pm-11:23 pm

1 stop7h 34m

$238

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Mon 11/10

4:14 pm-6:48 pm

Nonstop4h 34m

Seattle/Tacoma Intl

Tue 11/11

9:15 am-3:18 pm

Nonstop4h 03m

$247

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Sun 11/2

7:00 am-9:33 am

Nonstop4h 33m

Seattle/Tacoma Intl

Wed 11/5

9:15 am-3:18 pm

Nonstop4h 03m

$247

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Sun 11/9

7:00 am-9:33 am

Nonstop4h 33m

Seattle/Tacoma Intl

Tue 11/11

9:15 am-3:18 pm

Nonstop4h 03m

$247

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Wed 11/5

8:53 am-6:36 pm

2 stops11h 43m

Seattle/Tacoma Intl

Wed 11/12

11:15 am-6:57 pm

1 stop5h 42m

$249

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Thu 11/6

7:00 am-9:33 am

Nonstop4h 33m

Seattle/Tacoma Intl

Fri 11/14

9:15 am-3:18 pm

Nonstop4h 03m

$257

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/25

Showing 1-10 of 22 results
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Compare providers for flights from St. Louis to Seattle

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from St. Louis to Seattle in September.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy2 starsTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*3 stars
eDreamsPrice Accuracy3 starsTrust Score*3 stars
CheapflightsfaresPrice Accuracy2 starsTrust Score*1 star
CheapTicketsDealPrice Accuracy3 starsTrust Score*3 stars
JustAirTicketPrice Accuracy-Trust Score*3 stars
CheapfaremartPrice Accuracy-Trust Score*1 star

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on St. Louis-Seattle flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on St. Louis-Seattle flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from St. Louis-Seattle flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on St. Louis-Seattle flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for St. Louis-Seattle flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

The best insider tips for St. Louis to Seattle flights

Snippets provided in this section are AI-generated based on a summarization of Cheapflights-commissioned articles. The articles are presented as-is, for general informational purposes only, and may not be up-to-date. The opinions contained in the articles are original to the author and reflect their authentic experience, which may vary significantly from the experience of others.
Cheapflights partnered with top experts to bring you the best recommendations for your St. Louis to Seattle trip
Airports
STL

Security lines at STL are usually quick, averaging 5 to 10 minutes during off-peak times. Check real-time wait times online before heading to the airport.

Read more about STLby Taryn White
SEA

Take the Link light rail from SEA to downtown Seattle. It's affordable, runs every 10 minutes, and takes less than 40 minutes.

Read more about SEAby Brandon Schultz
Our travel experts
Taryn White

Taryn White

Expert on STL

Taryn White

Taryn White

Taryn White is a freelance travel writer, digital creator, and travel advisor who has visited nearly 100 countries and all 50 states. She’s familiar with many airports and enjoys beach hopping, boutique hotels, spa experiences, and exploring local culture. Her work has appeared in Travel + Leisure, Condé Nast Traveler, National Geographic, Smithsonian Magazine, AFAR, and more.

Read more
Brandon Schultz

Brandon Schultz

Expert on SEA

Brandon Schultz

Brandon Schultz

Brandon Schultz is an award-winning food and travel writer based in New York City. His work has appeared in Forbes, AAA, Thrillist, Travel + Leisure, and The Daily Meal, among many others, and he is the author of 6 books, including 3 cookbooks.

Read more

Best time to book a flight from St. Louis to Seattle

Have a flexible travel schedule? Discover the best time to fly to Seattle from St. Louis with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from St. Louis to Seattle

How far ahead should I book a flight from St. Louis to Seattle?

Use this chart to determine the optimal time to book a round-trip flight from St. Louis to Seattle. Price data was last updated on September 19, 2025.

The best time to book flights from St. Louis to Seattle is 69 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.

What is the cheapest month to book a flight from St. Louis to Seattle?

Currently, January is the cheapest month in which you can book a flight from St. Louis to Seattle (average of $238). Flying from St. Louis to Seattle in June is currently the most expensive (average of $388). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from STL to SEA?

Find hourly flight availability from St. Louis to Seattle. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated September 25, 2025.

Unlike at noon, when flights are generally more expensive, you can save up to 15% on flights from St. Louis to Seattle by exploring options for tickets in the afternoon.

What is the cheapest day to fly from St. Louis to Seattle?

Use this chart to determine the cheapest time to fly round-trip from St. Louis to Seattle. Price data was last updated on September 21, 2025.

Travelers seeking maximum savings on their St. Louis to Seattle flight should consider departing on Monday evenings when fares are most often at their lowest. Sunday at noon flights should be avoided if possible as fares are typically the most expensive at this time.

Reviews of airlines servicing Seattle

Get insights into the airlines that provide service to Seattle. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Seattle. Reviews last updated September 25, 2025.
Read through reviews of airlines operating flights from St. Louis to Seattle, such as Alaska Airlines, Southwest, and Delta. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Entertainment

7.0

Crew

8.5

Food

7.1

Comfort

7.8

Overall

8.0

Reviews

1 / 20
10.0
Excellent

Anonymous,Aug 2025

MFR - SEA

Great smooth flight. Was hour and half late though. Don't know why
Alaska Airlines
8.0
Very good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Entertainment

7.0

Crew

8.5

Food

7.1

Comfort

7.8

Overall

8.0

Reviews

1 / 20
10.0
Excellent

Anonymous,Aug 2025

MFR - SEA

Great smooth flight. Was hour and half late though. Don't know why
Southwest
8.0
Very good
4,246 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Entertainment

7.0

Crew

8.5

Food

7.1

Comfort

7.8

Overall

8.0

Reviews

1 / 20
10.0
Excellent

Anonymous,Aug 2025

MFR - SEA

Great smooth flight. Was hour and half late though. Don't know why
Delta
8.0
Very good
7,973 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Entertainment

7.0

Crew

8.5

Food

7.1

Comfort

7.8

Overall

8.0

Reviews

1 / 20
10.0
Excellent

Anonymous,Aug 2025

MFR - SEA

Great smooth flight. Was hour and half late though. Don't know why
Hawaiian Airlines
7.8
Good
2,751 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Entertainment

7.0

Crew

8.5

Food

7.1

Comfort

7.8

Overall

8.0

Reviews

1 / 20
10.0
Excellent

Anonymous,Aug 2025

MFR - SEA

Great smooth flight. Was hour and half late though. Don't know why
American Airlines
7.2
Good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Entertainment

7.0

Crew

8.5

Food

7.1

Comfort

7.8

Overall

8.0

Reviews

1 / 20
10.0
Excellent

Anonymous,Aug 2025

MFR - SEA

Great smooth flight. Was hour and half late though. Don't know why

Related info for your journey

Find useful and relevant information for your journey from St. Louis to Seattle. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airports do I use to fly from St. Louis to Seattle?

    Booking a flight from Lambert-St Louis (STL) to Seattle/Tacoma Intl (SEA) is your only option if you wish to fly from St. Louis to Seattle. On a typical day, there are 10 flights from Lambert-St Louis to Seattle/Tacoma Intl, all of which are around 4h 19m for a nonstop flight. You can also purchase a plane ticket from 7 airlines when you book a flight from Lambert-St Louis to Seattle.

  • How popular is this St. Louis to Seattle flight route?

    Within the past month, 52 users have taken a look at flights from Lambert-St Louis to Seattle/Tacoma Intl.

  • How long is the flight from St. Louis to Seattle?

    Airlines like Delta, United Airlines, and Alaska Airlines fly from St. Louis to Seattle in about 4h 33m. The time it takes to get you to your destination can typically vary by up to 3h 24m. There are 1704 mi between St. Louis and Seattle. When browsing for deals, the options you’ll see will be for both nonstop flights and flights with stops.

  • What are the cheapest airlines flying from St. Louis to Seattle round-trip?

    Currently priced at $94, Delta will fly you from St. Louis to Seattle and back. In addition to Delta, many other airlines offer competitively priced options for your trip. Search Cheapflights for deals from Frontier and Southwest - these airlines can fly you to your destination from $118 and $179, respectively. You may be able to fly from St. Louis to Seattle for 73% less than the average price by searching for these airlines.

  • What are the most reliable airlines from St. Louis to Seattle?

    The top 3 most reliable airlines when flying from St. Louis to Seattle are Qatar Airways (90%), Japan Airlines (90%) and Finnair (90%).

  • What are the cheapest flights from St. Louis to Seattle?

    Looking for the cheapest flight from St. Louis to Seattle? While on average our users pay $554, our data indicates the cheapest price to be $128. The most popular route (Lambert-St Louis - Seattle/Tacoma Intl), is priced around $141.

  • Can I find deals for flights from St. Louis to Seattle that include hotel bookings?

    Yes. In addition to deals on St. Louis to Seattle flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from St. Louis to Seattle?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from St. Louis to Seattle.

  • Can I find deals for business class flights from St. Louis to Seattle?

    Yes. Cheapflights offers flight deals from St. Louis to Seattle by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from St. Louis to Seattle?

    Currently, January is the cheapest month in which you can book a flight from St. Louis to Seattle (average of $238). Flying from St. Louis to Seattle in June is currently the most expensive (average of $388). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Traveling to a place near Seattle?

Book flights to Seattle if you plan to visit one of these locations
SeaTac
Tukwila
Tacoma
Lakewood
Ocean Shores
Lynnwood
Edmonds
Leavenworth
Renton
Lacey
Olympia
Kent
Federal Way
Cle Elum
Puyallup
Chehalis
Kirkland
Issaquah
Aberdeen
Shoreline

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Top 7 airlines flying from St. Louis to Seattle

Discover the top 7 airlines that operate flights from St. Louis to Seattle. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated September 25, 2025.
AirlineCheapestAverageFlexibilityOn-time
DeltaCheapest$94Average$235FlexibilityNo cancel feeOn-timeN/A
FrontierCheapest$118Average$225FlexibilityNo cancel feeOn-time62%
SouthwestCheapest$179Average$389FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$188Average$409FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$216Average$350FlexibilityNo cancel feeOn-time69%
Hawaiian AirlinesCheapest$237Average$381FlexibilityNo cancel feeOn-time85%
Alaska AirlinesCheapest$237Average$393FlexibilityNo cancel feeOn-time75%

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