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St. Charles

$63+ 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 1/9. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — STL
Nov 29 — Dec 61
Sat 11/29
Sat 12/6
1 adult, Economy
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Cheapflights Tip: The best prices from Seattle/Tacoma Intl to St. Charles are usually found in September or January, booked 57 days in advance, depart on a Thursday or Friday and return on a Tuesday

Cheap 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 October 30, 2025.

Most accurate provider

eDreams
3 stars

Most trusted provider

eDreams
3 stars

Round-trip from

$233
(American Airlines)

One-way from

$63
(Trip.com)

Popular in

December

Cheapest in

September

Average price

$345
Provider with most accurate pricing for Seattle/Tacoma Intl-Lambert-St Louis flight deals.
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Provider most trusted by Cheapflights users for Seattle/Tacoma Intl-Lambert-St Louis flights.
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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. 2% potential increase in price ($9 potential increase over avg. RT price).
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Cheapest flight prices on average. 2% potential price decrease ($8 potential savings vs. average RT price).
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Average for round-trip flights in October 2025
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Find 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 October 30, 2025.

This Southwest deal was found by Cheapflights users on 10/29. 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 11/236:35 amSEA - STL
1 stop6h 30mSouthwest
Thu 11/276:25 amSTL - SEA
1 stop6h 30mSouthwest
Deal found 10/29$237
This Kiwi.com deal was found by Cheapflights users on 10/28. 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.
Mon 11/172:22 pmSEA - STL
1 stop16h 45mFrontier
Thu 11/207:57 pmSTL - SEA
1 stop17h 59mFrontier
Deal found 10/28$242
This Delta deal was found by Cheapflights users on 10/29. 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 11/1711:10 pmSEA - STL
1 stop8h 36mDelta
Thu 11/206:34 amSTL - SEA
1 stop8h 22mDelta
Deal found 10/29$243
This Kiwi.com deal was found by Cheapflights users on 10/30. 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.
Fri 11/1411:43 amSEA - STL
1 stop26h 13mFrontier
Sun 11/167:02 pmSTL - SEA
2 stops17h 53mFrontier
Deal found 10/30$246
This Alaska Airlines deal was found by Cheapflights users on 10/30. 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.
Wed 12/38:34 amSEA - STL
Nonstop3h 53mAlaska Airlines
Sun 12/73:23 pmSTL - SEA
Nonstop4h 36mAlaska Airlines
Deal found 10/30$247
This Kiwi.com deal was found by Cheapflights users on 10/30. 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.
Thu 11/1312:58 pmSEA - STL
1 stop18h 09mFrontier
Mon 11/179:07 pmSTL - SEA
2 stops17h 00mFrontier
Deal found 10/30$249
This Southwest deal was found by Cheapflights users on 10/30. 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.
Tue 12/25:40 amSEA - STL
1 stop11h 15mSouthwest
Thu 12/44:00 pmSTL - SEA
1 stop7h 50mSouthwest
Deal found 10/30$252
This Alaska Airlines deal was found by Cheapflights users on 10/30. 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.
Thu 12/46:05 pmSEA - STL
Nonstop3h 54mAlaska Airlines
Sun 12/77:00 amSTL - SEA
Nonstop4h 40mAlaska Airlines
Deal found 10/30$257
This American Airlines deal was found by Cheapflights users on 10/30. 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.
Mon 12/112:59 amSEA - STL
1 stop9h 38mAmerican Airlines
Sat 12/611:35 amSTL - SEA
1 stop9h 20mAmerican Airlines
Deal found 10/30$262
This Kiwi.com deal was found by Cheapflights users on 10/30. 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.
Fri 11/1411:43 amSEA - STL
1 stop26h 13mFrontier
Mon 11/179:07 pmSTL - SEA
2 stops17h 00mFrontier
Deal found 10/30$264
This Kiwi.com deal was found by Cheapflights users on 10/29. 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.
Tue 11/41:37 pmSEA - STL
1 stop17h 30mFrontier
Mon 11/179:07 pmSTL - SEA
2 stops17h 00mFrontier
Deal found 10/29$265

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 October 30, 2025.
Use the filters below to find and compare flights from Seattle to St. Charles that are best for you.

Fly from

Seattle

Fly to

St. Charles

Route

Depart

Return

Price

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sun 11/23

6:35 am-3:05 pm

1 stop6h 30m

Lambert-St Louis

Thu 11/27

6:25 am-10:55 am

1 stop6h 30m

$237

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Wed 12/3

8:34 am-2:27 pm

Nonstop3h 53m

Lambert-St Louis

Sun 12/7

7:00 am-9:40 am

Nonstop4h 40m

$247

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Thu 12/4

6:05 pm-11:59 pm

Nonstop3h 54m

Lambert-St Louis

Sun 12/7

7:00 am-9:40 am

Nonstop4h 40m

$257

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Tue 11/18

9:15 am-3:18 pm

Nonstop4h 03m

Lambert-St Louis

Thu 11/20

7:00 am-9:33 am

Nonstop4h 33m

$277

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Fri 11/28

10:53 am-7:39 pm

1 stop6h 46m

Lambert-St Louis

Fri 12/5

4:37 pm-12:50 am

2 stops10h 13m

$283

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Fri 11/28

9:27 am-3:19 pm

Nonstop3h 52m

Lambert-St Louis

Fri 12/5

7:00 am-9:40 am

Nonstop4h 40m

$289

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Fri 11/28

5:22 pm-10:02 am

2 stops14h 40m

Lambert-St Louis

Fri 12/5

7:43 pm-11:53 am

1 stop18h 10m

$295

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Tue 12/30

5:00 am-3:15 pm

1 stop8h 15m

Lambert-St Louis

Fri 1/2

6:45 pm-12:35 am

1 stop7h 50m

$297

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sat 11/15

11:10 pm-9:46 am

1 stop8h 36m

Lambert-St Louis

Mon 11/17

5:34 pm-12:01 am

1 stop8h 27m

$298

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Thu 11/13

8:22 pm-11:24 am

1 stop13h 02m

Lambert-St Louis

Sun 11/16

2:42 pm-10:55 am

2 stops22h 13m

$301

Flights are sorted by cheapest round-trip flights first.

Deals found on 10/27

Showing 1-10 of 22 results
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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 October 24, 2025.

The best time to book flights from Seattle to St. Charles is 57 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, July is the cheapest month in which you can book a flight from Seattle to St. Charles (average of $163). Flying from Seattle to St. Charles in March is currently the most expensive (average of $230). 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 October 30, 2025.

It’s typically best to fly out from Seattle to St. Charles at noon. Doing so could potentially save you 31% on the flight price compared to flying in the morning, which is usually more expensive.

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

Use this chart to determine the cheapest time to fly round-trip from Seattle to St. Charles. Price data was last updated on December 16, 2024.

Travelers seeking maximum savings on their Seattle to St. Charles flight should consider departing on Thursday at noon 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 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 October 30, 2025.
Get a feel of what it's like to fly with Alaska Airlines, Southwest, and Delta 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.
Alaska Airlines
8.0
Very good
11,220 reviews

Overall

8.0

Boarding

8.1

Entertainment

7.0

Crew

8.5

Comfort

7.8

Food

7.1

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
Alaska Airlines
8.0
Very good
11,220 reviews
Alaska Airlines
8.0
Very good
11,220 reviews

Overall

8.0

Boarding

8.1

Entertainment

7.0

Crew

8.5

Comfort

7.8

Food

7.1

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
Southwest
8.0
Very good
4,243 reviews
Alaska Airlines
8.0
Very good
11,220 reviews

Overall

8.0

Boarding

8.1

Entertainment

7.0

Crew

8.5

Comfort

7.8

Food

7.1

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
Delta
7.9
Good
7,998 reviews
Alaska Airlines
8.0
Very good
11,220 reviews

Overall

8.0

Boarding

8.1

Entertainment

7.0

Crew

8.5

Comfort

7.8

Food

7.1

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
Hawaiian Airlines
7.8
Good
2,798 reviews
Alaska Airlines
8.0
Very good
11,220 reviews

Overall

8.0

Boarding

8.1

Entertainment

7.0

Crew

8.5

Comfort

7.8

Food

7.1

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
American Airlines
7.2
Good
11,034 reviews
Alaska Airlines
8.0
Very good
11,220 reviews

Overall

8.0

Boarding

8.1

Entertainment

7.0

Crew

8.5

Comfort

7.8

Food

7.1

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.

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 is 1 flight 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 5 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, Alaska Airlines, and United Airlines fly from Seattle to St. Charles in about 3h 53m. The time it takes to get you to your destination can typically vary by up to 2h 53m. The distance from Seattle to St. Charles is about 1704 mi. This flight may include one or multiple stops.

  • 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 Finnair (100%), Alaska Airlines (86%) and Hawaiian Airlines (86%).

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

    On average you can expect to pay $574 for a flight from Seattle to St. Charles. The cheapest flight overall is $118 while the most popular route, (Seattle/Tacoma Intl - Lambert-St Louis) is currently priced at $163.

  • 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, July is the cheapest month in which you can book a flight from Seattle to St. Charles (average of $163). Flying from Seattle to St. Charles in March is currently the most expensive (average of $230). 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.

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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 October 30, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$134Average$285FlexibilityNo cancel feeOn-time62%
DeltaCheapest$134Average$289FlexibilityNo cancel feeOn-timeN/A
SouthwestCheapest$169Average$330FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$186Average$546FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$216Average$340FlexibilityNo cancel feeOn-time69%
Hawaiian AirlinesCheapest$219Average$395FlexibilityNo cancel feeOn-time85%
Alaska AirlinesCheapest$246Average$417FlexibilityNo cancel feeOn-time75%

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