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$84+ 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 9/20. Fares are subject to change and may not be available on all flights or dates of travel.
STL — SEA
Aug 18 — Aug 251
Mon 8/18
Mon 8/25
1 adult, Economy
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Cheapflights Tip: The best prices from Lambert-St Louis to Seattle/Tacoma Intl are usually found in September or October, 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 August 13, 2025.

Round-trip from

$231
(United Airlines)

One-way from

$84
(United Airlines)

Popular in

July

Cheapest in

September

Average price

$359

Good round-trip deal

$323 or less

Good one-way deal

$216 or less
From Lambert-St Louis to Seattle/Tacoma Intl
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One-way flight from Lambert-St Louis to Seattle/Tacoma Intl
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Highest demand for flights based on searches. 14% potential increase in price ($59 potential increase over avg. RT price).
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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 August 2025
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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 August 13, 2025.

This United Airlines deal was found by Cheapflights users on 8/12. 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 10/281:35 pmSTL - SEA
2 stops9h 16mUnited Airlines
Sat 11/17:00 amSEA - STL
1 stop6h 46mUnited Airlines
Deal found 8/12$231
This CheapOair deal was found by Cheapflights users on 8/12. 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 9/27:54 pmSTL - SEA
1 stop29h 07mFrontier
Thu 9/116:12 amSEA - STL
1 stop24h 54mFrontier
Deal found 8/12$235
This CheapOair deal was found by Cheapflights users on 8/12. 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.
Thu 9/187:55 pmSTL - SEA
1 stop6h 35mFrontier
Mon 9/226:12 amSEA - STL
1 stop24h 54mFrontier
Deal found 8/12$236
This American Airlines deal was found by Cheapflights users on 8/11. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/63:59 pmSTL - SEA
1 stop7h 24mAmerican Airlines
Sat 9/136:11 amSEA - STL
1 stop9h 49mAmerican Airlines
Deal found 8/11$238
This CheapOair deal was found by Cheapflights users on 8/11. 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.
Mon 9/87:55 pmSTL - SEA
1 stop29h 04mFrontier
Thu 9/116:12 amSEA - STL
1 stop24h 54mFrontier
Deal found 8/11$240
This CheapOair deal was found by Cheapflights users on 8/13. 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 8/197:54 pmSTL - SEA
1 stop29h 07mFrontier
Thu 8/214:40 pmSEA - STL
1 stop14h 31mFrontier
Deal found 8/13$242
This CheapOair deal was found by Cheapflights users on 8/11. 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.
Thu 8/217:54 pmSTL - SEA
1 stop15h 40mFrontier
Mon 8/254:40 pmSEA - STL
1 stop14h 31mFrontier
Deal found 8/11$243
This FlightHub deal was found by Cheapflights users on 8/11. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/197:54 pmSTL - SEA
1 stop29h 07mFrontier
Mon 8/254:40 pmSEA - STL
1 stop14h 31mFrontier
Deal found 8/11$244
This CheapOair deal was found by Cheapflights users on 8/12. 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.
Thu 9/117:55 pmSTL - SEA
1 stop6h 35mFrontier
Thu 9/186:12 amSEA - STL
1 stop24h 54mFrontier
Deal found 8/12$245
This CheapOair deal was found by Cheapflights users on 8/12. 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.
Mon 8/187:29 pmSTL - SEA
1 stop29h 32mFrontier
Thu 8/214:40 pmSEA - STL
1 stop14h 31mFrontier
Deal found 8/12$246
This American Airlines deal was found by Cheapflights users on 8/13. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/85:00 amSTL - SEA
1 stop9h 53mAmerican Airlines
Sun 11/912:59 amSEA - STL
1 stop7h 38mAmerican Airlines
Deal found 8/13$247
This Delta deal was found by Cheapflights users on 8/11. 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.
Mon 9/82:25 pmSTL - SEA
1 stop6h 35mDelta
Wed 9/106:10 amSEA - STL
1 stop6h 14mDelta
Deal found 8/11$248

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 August 13, 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

Tue 10/28

1:35 pm-8:51 pm

2 stops9h 16m

Seattle/Tacoma Intl

Sat 11/1

7:00 am-3:46 pm

1 stop6h 46m

$231

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Thu 9/18

7:55 pm-12:30 am

1 stop6h 35m

Seattle/Tacoma Intl

Mon 9/22

6:12 am-9:06 am

1 stop24h 54m

$236

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Sat 9/6

3:59 pm-9:23 pm

1 stop7h 24m

Seattle/Tacoma Intl

Sat 9/13

6:11 am-6:00 pm

1 stop9h 49m

$238

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Tue 9/2

7:54 pm-11:01 pm

1 stop29h 07m

Seattle/Tacoma Intl

Sun 9/14

6:12 am-9:06 am

1 stop24h 54m

$238

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Tue 9/30

7:55 pm-10:59 pm

1 stop29h 04m

Seattle/Tacoma Intl

Sun 10/5

6:12 am-9:06 am

1 stop24h 54m

$238

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Tue 9/9

7:55 pm-10:59 pm

1 stop29h 04m

Seattle/Tacoma Intl

Sun 9/14

6:12 am-9:06 am

1 stop24h 54m

$238

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Tue 11/4

7:52 pm-11:02 pm

1 stop29h 10m

Seattle/Tacoma Intl

Sun 11/9

6:00 am-9:07 am

1 stop25h 07m

$238

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Mon 9/29

7:55 pm-12:30 am

1 stop6h 35m

Seattle/Tacoma Intl

Tue 9/30

8:36 am-2:39 pm

Nonstop4h 03m

$240

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Sat 9/20

5:49 pm-10:59 pm

1 stop7h 10m

$84

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Tue 9/23

5:49 pm-10:59 pm

1 stop7h 10m

$84

Flights are sorted by cheapest round-trip flights first.

Deals found on 8/12

Showing 1-10 of 18 results
1
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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 August 8, 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 $389). 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 August 13, 2025.

Unlike in the morning, when flights are generally more expensive, you can save up to 13% 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 August 10, 2025.

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

Weekly flight availability from St. Louis to Seattle

Explore weekly flight availability from St. Louis to Seattle. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated August 13, 2025.

The most flights from STL to SEA are scheduled on a Wednesday (16 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (9 on average).

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 August 13, 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

Entertainment

7.0

Overall

8.0

Boarding

8.1

Food

7.1

Comfort

7.8

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Anonymous,Jul 2025

EUG - SEA

Mobility support was fabulous No flight entertainment that I was aware of.
Alaska Airlines
8.0
Very good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.0

Overall

8.0

Boarding

8.1

Food

7.1

Comfort

7.8

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Anonymous,Jul 2025

EUG - SEA

Mobility support was fabulous No flight entertainment that I was aware of.
Southwest
8.0
Very good
4,246 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.0

Overall

8.0

Boarding

8.1

Food

7.1

Comfort

7.8

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Anonymous,Jul 2025

EUG - SEA

Mobility support was fabulous No flight entertainment that I was aware of.
Delta
8.0
Very good
7,979 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.0

Overall

8.0

Boarding

8.1

Food

7.1

Comfort

7.8

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Anonymous,Jul 2025

EUG - SEA

Mobility support was fabulous No flight entertainment that I was aware of.
Hawaiian Airlines
7.8
Good
2,655 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.0

Overall

8.0

Boarding

8.1

Food

7.1

Comfort

7.8

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Anonymous,Jul 2025

EUG - SEA

Mobility support was fabulous No flight entertainment that I was aware of.
American Airlines
7.2
Good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.0

Overall

8.0

Boarding

8.1

Food

7.1

Comfort

7.8

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Anonymous,Jul 2025

EUG - SEA

Mobility support was fabulous No flight entertainment that I was aware of.

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 12 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, 50 users have taken a look at flights from Lambert-St Louis to Seattle/Tacoma Intl.

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

    Currently priced at $231, United Airlines will fly you from St. Louis to Seattle and back. In addition to United Airlines, many other airlines offer competitively priced options for your trip. Check Cheapflights for deals on Frontier for as low as $235. You may be able to fly from St. Louis to Seattle for 35% 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 Finnair (91%), Japan Airlines (90%) and Qatar Airways (88%).

  • 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 $732, our data indicates the cheapest price to be $124. The most popular route (Lambert-St Louis - Seattle/Tacoma Intl), is priced around $177.

  • 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 $389). 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
Ocean Shores
Lakewood
Lynnwood
Lacey
Leavenworth
Renton
Olympia
Puyallup
Kent
Cle Elum
Chehalis
Kirkland
Issaquah
Aberdeen
Shoreline
Federal Way
Shelton

Browse thousands of different options on Cheapflights for your next trip

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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 August 13, 2025.
AirlineCheapestAverageFlexibilityOn-time
DeltaCheapest$94Average$244FlexibilityNo cancel feeOn-timeN/A
FrontierCheapest$100Average$211FlexibilityNo cancel feeOn-time62%
SouthwestCheapest$179Average$389FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$188Average$429FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$216Average$351FlexibilityNo cancel feeOn-time69%
Alaska AirlinesCheapest$236Average$394FlexibilityNo cancel feeOn-time75%
Hawaiian AirlinesCheapest$238Average$395FlexibilityNo cancel feeOn-time85%

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