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St. Charles

$85+ Cheap flights from Seattle (SEA) to St. Charles, MO

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 4/15. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — STL
abr. 27 — may. 41
lun. 4/27
lun. 5/4
1 adult, Economy
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Cheapflights Tip: The best prices from Seattle/Tacoma Intl to St. Charles are usually found in January or February, booked 67 days in advance, depart on a Tuesday or Wednesday and return on a Tuesday

Cheap flight deals from Seattle to St. Charles

Cheapest flights from Seattle to St. Charles
Explore the most affordable flight options available from Seattle to St. Charles. Find the lowest fares from popular airlines and budget airlines, with prices last updated on marzo 28, 2026.

This Kiwi.com deal was found by Cheapflights users on 3/27. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
vie. 4/247:12 pm
SEA
-
STL
1 stop22h 20m
Frontier
jue. 4/309:55 pm
STL
-
SEA
2 stops13h 57m
Frontier
Deal found 3/27$268
This Delta deal was found by Cheapflights users on 3/26. 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.
lun. 4/201:30 pm
SEA
-
STL
1 stop8h 55m
Delta
sáb. 4/256:20 am
STL
-
SEA
1 stop7h 55m
Delta
Deal found 3/26$269
This Kiwi.com deal was found by Cheapflights users on 3/23. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
vie. 5/17:12 pm
SEA
-
STL
2 stops18h 09m
Frontier
lun. 5/48:17 pm
STL
-
SEA
1 stop15h 32m
Frontier
Deal found 3/23$271
This CheapOair deal was found by Cheapflights users on 3/25. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
vie. 3/279:36 pm
SEA
-
STL
1 stop11h 43m
Frontier
vie. 4/108:16 pm
STL
-
SEA
1 stop17h 21m
Frontier
Deal found 3/25$272
This Southwest deal was found by Cheapflights users on 3/25. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
jue. 4/2311:55 pm
SEA
-
STL
1 stop8h 20m
Southwest
dom. 4/268:25 am
STL
-
SEA
1 stop8h 20m
Southwest
Deal found 3/25$274
This Southwest deal was found by Cheapflights users on 3/25. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
mié. 4/226:50 am
SEA
-
STL
2 stops9h 15m
Southwest
mié. 4/295:30 am
STL
-
SEA
2 stops14h 30m
Southwest
Deal found 3/25$275
This Kiwi.com deal was found by Cheapflights users on 3/24. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
vie. 4/247:12 pm
SEA
-
STL
1 stop22h 20m
Frontier
vie. 5/17:01 pm
STL
-
SEA
2 stops16h 26m
Frontier
Deal found 3/24$276
This Alaska Airlines deal was found by Cheapflights users on 3/27. 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
sáb. 4/255:57 pm
SEA
-
STL
Nonstop4h 02m
Alaska Airlines
mié. 4/297:00 am
STL
-
SEA
Nonstop4h 32m
Alaska Airlines
Deal found 3/27$277
This Kiwi.com deal was found by Cheapflights users on 3/24. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
vie. 4/2410:11 pm
SEA
-
STL
2 stops19h 21m
Frontier
sáb. 5/28:17 pm
STL
-
SEA
1 stop15h 10m
Frontier
Deal found 3/24$278
This Delta deal was found by Cheapflights users on 3/26. 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.
lun. 4/2011:14 pm
SEA
-
STL
1 stop8h 28m
Delta
vie. 4/245:35 pm
STL
-
SEA
1 stop8h 19m
Delta
Deal found 3/26$279
This United Airlines deal was found by Cheapflights users on 3/25. 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.
mar. 7/2111:52 pm
SEA
-
STL
1 stop6h 49m
United Airlines
vie. 7/247:23 pm
STL
-
SEA
1 stop7h 57m
United Airlines
Deal found 3/25$281
This Southwest deal was found by Cheapflights users on 3/25. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
mié. 5/276:50 am
SEA
-
STL
2 stops9h 15m
Southwest
vie. 6/56:45 pm
STL
-
SEA
1 stop8h 55m
Southwest
Deal found 3/25$283

Find flight deals from Seattle to St. Charles

Keep the following information in mind while searching for Seattle to St. Charles flight deals. Data was last updated marzo 28, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$268
(Kiwi.com)

One-way from

$85
(American Airlines)

Popular in

December

Cheapest in

January

Average price

$431
Provider with most accurate pricing for Seattle/Tacoma Intl-Lambert-St Louis flight deals.
Search Deals
Provider most trusted by Cheapflights users for Seattle/Tacoma Intl-Lambert-St Louis flights.
Search Deals
From Seattle/Tacoma Intl to St. Charles
Search Deals
One-way flight from Seattle/Tacoma Intl to St. Charles
Search Deals
Highest demand for flights based on searches. 4% potential increase in price ($18 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 4% potential price decrease ($16 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in March 2026
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Seattle to St. Charles 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 marzo 28, 2026.
Use the filters below to find and compare flights from Seattle to St. Charles that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

mié. 4/22

6:50 am-6:05 pm

2 stops9h 15m

Lambert-St Louis

mié. 4/29

5:30 am-6:00 pm

2 stops14h 30m

$275
Quickest round-trip

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

mar. 5/5

5:57 pm-11:59 pm

Nonstop4h 02m

Lambert-St Louis

mié. 5/6

4:46 pm-7:15 pm

Nonstop4h 29m

$277

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

jue. 4/23

11:55 pm-9:05 am

1 stop7h 10m

Lambert-St Louis

lun. 4/27

5:45 am-5:00 pm

2 stops13h 15m

$297

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

dom. 5/3

11:45 am-1:15 am

2 stops11h 30m

Lambert-St Louis

mié. 5/6

5:30 am-6:00 pm

2 stops14h 30m

$339

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

dom. 5/3

5:57 pm-11:59 pm

Nonstop4h 02m

Lambert-St Louis

mar. 5/5

4:46 pm-7:15 pm

Nonstop4h 29m

$342

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

mar. 4/7

5:30 am-1:17 pm

1 stop5h 47m

Lambert-St Louis

lun. 4/13

2:20 pm-6:30 pm

1 stop6h 10m

$343

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

mié. 4/8

5:30 am-1:17 pm

1 stop5h 47m

Lambert-St Louis

lun. 4/13

2:20 pm-6:30 pm

1 stop6h 10m

$343

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

dom. 5/3

10:53 pm-8:39 am

1 stop7h 46m

Lambert-St Louis

mar. 5/5

6:30 am-11:39 am

1 stop7h 09m

$389

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

vie. 5/1

6:30 am-10:40 pm

2 stops14h 10m

Lambert-St Louis

lun. 5/4

5:45 am-5:00 pm

2 stops13h 15m

$406
Cheapest one-way

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

mar. 6/9

10:45 pm-7:45 am

1 stop7h 00m

$85

Flights are sorted by cheapest round-trip flights first.

Deals found on 3/24

Showing 1-10 of 19 resultsSorted by cheapest first
1
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Best time to book a flight from Seattle to St. Charles

Have a flexible travel schedule? Discover the best time to fly to St. Charles from Seattle 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 Seattle to St. Charles

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

Use this chart to determine the optimal time to book a round-trip flight from Seattle to St. Charles. Price data was last updated on March 13, 2026.

The best time to book flights from Seattle to St. Charles is 67 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 Seattle to St. Charles?

Currently, January is the cheapest month in which you can book a flight from Seattle to St. Charles (average of $152). Flying from Seattle to St. Charles in December is currently the most expensive (average of $260). 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 SEA to CH5?

Find hourly flight availability from Seattle to St. Charles. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated marzo 28, 2026.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Seattle to St. Charles as you normally would.

How much does it cost to fly round-trip from Seattle to St. Charles?

Reviews of airlines servicing St. Charles

Get insights into the airlines that provide service to St. Charles. 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 St. Charles. Reviews last updated marzo 28, 2026.
Get a feel of what it's like to fly with Southwest,Alaska Airlines, andDelta from Seattle to St. Charles by reading reviews from past customers. Users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,333 reviews

Overall

8.0

Boarding

8.1

Comfort

8.0

Food

7.0

Crew

8.6

Entertainment

7.5

Reviews

1 / 20
2.0
Mediocre

Dominic,Mar 2026

MCO - SMF

I had to try and sleep on the floor of the Austin airport. I spent 12 hours there. The airline policies were so poor, that a near violent argument broke out between the people in front of me and the flight attendants - making for a super stressful situation at 30,000 feet. Garbage airline choice by Kayak Garbage idea to book a flight with a layover. Next time I will pay for a quality booking myself, and somehow force the company to reimburse it.
Southwest
8.0
Very good
4,333 reviews
Southwest
8.0
Very good
4,333 reviews

Overall

8.0

Boarding

8.1

Comfort

8.0

Food

7.0

Crew

8.6

Entertainment

7.5

Reviews

1 / 20
2.0
Mediocre

Dominic,Mar 2026

MCO - SMF

I had to try and sleep on the floor of the Austin airport. I spent 12 hours there. The airline policies were so poor, that a near violent argument broke out between the people in front of me and the flight attendants - making for a super stressful situation at 30,000 feet. Garbage airline choice by Kayak Garbage idea to book a flight with a layover. Next time I will pay for a quality booking myself, and somehow force the company to reimburse it.
Alaska Airlines
7.9
Good
12,134 reviews
Southwest
8.0
Very good
4,333 reviews

Overall

8.0

Boarding

8.1

Comfort

8.0

Food

7.0

Crew

8.6

Entertainment

7.5

Reviews

1 / 20
2.0
Mediocre

Dominic,Mar 2026

MCO - SMF

I had to try and sleep on the floor of the Austin airport. I spent 12 hours there. The airline policies were so poor, that a near violent argument broke out between the people in front of me and the flight attendants - making for a super stressful situation at 30,000 feet. Garbage airline choice by Kayak Garbage idea to book a flight with a layover. Next time I will pay for a quality booking myself, and somehow force the company to reimburse it.
Delta
7.9
Good
8,357 reviews
Southwest
8.0
Very good
4,333 reviews

Overall

8.0

Boarding

8.1

Comfort

8.0

Food

7.0

Crew

8.6

Entertainment

7.5

Reviews

1 / 20
2.0
Mediocre

Dominic,Mar 2026

MCO - SMF

I had to try and sleep on the floor of the Austin airport. I spent 12 hours there. The airline policies were so poor, that a near violent argument broke out between the people in front of me and the flight attendants - making for a super stressful situation at 30,000 feet. Garbage airline choice by Kayak Garbage idea to book a flight with a layover. Next time I will pay for a quality booking myself, and somehow force the company to reimburse it.
Hawaiian Airlines
7.8
Good
2,837 reviews
Southwest
8.0
Very good
4,333 reviews

Overall

8.0

Boarding

8.1

Comfort

8.0

Food

7.0

Crew

8.6

Entertainment

7.5

Reviews

1 / 20
2.0
Mediocre

Dominic,Mar 2026

MCO - SMF

I had to try and sleep on the floor of the Austin airport. I spent 12 hours there. The airline policies were so poor, that a near violent argument broke out between the people in front of me and the flight attendants - making for a super stressful situation at 30,000 feet. Garbage airline choice by Kayak Garbage idea to book a flight with a layover. Next time I will pay for a quality booking myself, and somehow force the company to reimburse it.
American Airlines
7.1
Good
11,519 reviews
Southwest
8.0
Very good
4,333 reviews

Overall

8.0

Boarding

8.1

Comfort

8.0

Food

7.0

Crew

8.6

Entertainment

7.5

Reviews

1 / 20
2.0
Mediocre

Dominic,Mar 2026

MCO - SMF

I had to try and sleep on the floor of the Austin airport. I spent 12 hours there. The airline policies were so poor, that a near violent argument broke out between the people in front of me and the flight attendants - making for a super stressful situation at 30,000 feet. Garbage airline choice by Kayak Garbage idea to book a flight with a layover. Next time I will pay for a quality booking myself, and somehow force the company to reimburse it.

Related info for your journey

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

  • What airport do you fly from for flights from Seattle to St. Charles?

    If you book a flight to St. Charles from Seattle, you will be flying from Seattle/Tacoma Intl, which is the city’s only airport. Seattle/Tacoma Intl (SEA) is located 11.4 mi from the center of Seattle. There are 2 flights from Seattle/Tacoma Intl to St. Charles per day from 7 different airlines.

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

    This flight path from Seattle/Tacoma Intl to St. Charles was viewed by 4 users in the past month. Keep an eye out for changes in search interest prior to high and low season.

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

    Airlines like Southwest and Alaska Airlines fly from Seattle to St. Charles in about 4h 02m. The time it takes to get you to your destination can typically vary by up to 5h 13m. The distance from Seattle to St. Charles is about 1704 mi. This flight may include one or multiple stops.

  • What are the cheapest airlines to fly from Seattle to St. Charles one-way?

    To fly one-way, consider booking your trip with United Airlines, which is currently one of the cheapest options available, starting at $74. American Airlines flights start at $88 while deals on Southwest start at $88 one-way.

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

    The top 3 most reliable airlines when flying from Seattle to St. Charles are Air Tahiti Nui (96%), Alaska Airlines (96%) and Hawaiian Airlines (96%).

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

    On average you can expect to pay $382 for a flight from Seattle to St. Charles. The cheapest flight overall is $128 while the most popular route, (Seattle/Tacoma Intl - Lambert-St Louis) is currently priced at $203.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from Seattle to St. Charles 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 Seattle to St. Charles?

    Currently, January is the cheapest month in which you can book a flight from Seattle to St. Charles (average of $152). Flying from Seattle to St. Charles in December is currently the most expensive (average of $260). 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

Browse thousands of different options on Cheapflights for your next trip

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Top 7 airlines flying from Seattle to St. Charles

Discover the top 7 airlines that operate flights from Seattle to St. Charles. 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 marzo 28, 2026.
AirlineCheapestAverageFlexibilityOn-time
DeltaCheapest$94Average$265FlexibilityNo cancel feeOn-timeN/A
FrontierCheapest$136Average$218FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$157Average$368FlexibilityNo cancel feeOn-time69%
Hawaiian AirlinesCheapest$181Average$380FlexibilityNo cancel feeOn-time85%
SouthwestCheapest$182Average$341FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$188Average$525FlexibilityNo cancel feeOn-time71%
Alaska AirlinesCheapest$226Average$402FlexibilityNo cancel feeOn-time75%

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