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St. Charles

$68+ 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
Jan 14 — Jan 211
Wed 1/14
Wed 1/21
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 September, booked 67 days in advance, depart on a Thursday or Tuesday 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 December 15, 2025.

This Delta deal was found by Cheapflights users on 12/14. 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.
Wed 12/315:25 amSEA - STL
1 stop5h 58mDelta
Thu 1/85:00 pmSTL - SEA
1 stop8h 22mDelta
Deal found 12/14$293
This Alaska Airlines deal was found by Cheapflights users on 12/14. 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 12/316:05 pmSEA - STL
Nonstop3h 54mAlaska Airlines
Wed 1/72:50 pmSTL - SEA
Nonstop4h 35mAlaska Airlines
Deal found 12/14$312
This Alaska Airlines deal was found by Cheapflights users on 12/15. 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 12/316:05 pmSEA - STL
Nonstop3h 54mAlaska Airlines
Mon 1/55:26 pmSTL - SEA
Nonstop4h 33mAlaska Airlines
Deal found 12/15$322
This Delta deal was found by Cheapflights users on 12/15. 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.
Wed 12/315:25 amSEA - STL
1 stop5h 58mDelta
Mon 1/57:00 amSTL - SEA
2 stops15h 48mDelta
Deal found 12/15$327
This Alaska Airlines deal was found by Cheapflights users on 12/15. 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.
Mon 12/296:05 pmSEA - STL
Nonstop3h 54mAlaska Airlines
Mon 1/55:26 pmSTL - SEA
Nonstop4h 33mAlaska Airlines
Deal found 12/15$333
This Delta deal was found by Cheapflights users on 12/15. 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 12/2910:55 pmSEA - STL
1 stop8h 29mDelta
Mon 1/57:00 amSTL - SEA
2 stops15h 48mDelta
Deal found 12/15$338
This Alaska Airlines deal was found by Cheapflights users on 12/13. 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/286:05 pmSEA - STL
Nonstop3h 54mAlaska Airlines
Mon 1/55:26 pmSTL - SEA
Nonstop4h 33mAlaska Airlines
Deal found 12/13$353
This Southwest deal was found by Cheapflights users on 12/14. 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 12/306:45 amSEA - STL
1 stop8h 45mSouthwest
Tue 1/62:15 pmSTL - SEA
1 stop10h 50mSouthwest
Deal found 12/14$354
This Delta deal was found by Cheapflights users on 12/13. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/286:00 amSEA - STL
1 stop9h 01mDelta
Mon 1/57:00 amSTL - SEA
2 stops15h 48mDelta
Deal found 12/13$373

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 December 15, 2025.

Most accurate provider

eDreams
3 stars

Most trusted provider

eDreams
3 stars

Round-trip from

$237
(Alaska Airlines)

One-way from

$68
(Kiwi.com)

Popular in

December

Cheapest in

January

Average price

$606
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. 8% potential increase in price ($35 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 5% potential price decrease ($20 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
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 December 15, 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

Thu 1/22

7:55 am-1:54 pm

Nonstop3h 59m

Lambert-St Louis

Mon 1/26

2:50 pm-5:25 pm

Nonstop4h 35m

$237

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Mon 1/5

6:05 pm-11:59 pm

Nonstop3h 54m

Lambert-St Louis

Thu 1/8

2:50 pm-5:25 pm

Nonstop4h 35m

$237

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Fri 1/9

3:35 pm-11:25 pm

1 stop5h 50m

Lambert-St Louis

Sun 1/11

6:35 am-2:21 pm

1 stop9h 46m

$238

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Thu 1/22

5:00 am-4:03 pm

2 stops9h 03m

Lambert-St Louis

Mon 1/26

9:57 am-4:01 pm

1 stop8h 04m

$242

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Mon 1/5

11:15 pm-9:35 pm

2 stops20h 20m

Lambert-St Louis

Sat 1/10

6:00 am-2:21 pm

1 stop10h 21m

$252

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Fri 4/24

6:00 pm-11:55 pm

Nonstop3h 55m

Lambert-St Louis

Tue 4/28

7:00 am-9:31 am

Nonstop4h 31m

$269

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Wed 4/22

6:00 pm-11:55 pm

Nonstop3h 55m

Lambert-St Louis

Fri 5/1

7:00 am-9:31 am

Nonstop4h 31m

$269

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Thu 3/26

8:00 am-2:11 pm

Nonstop4h 11m

Lambert-St Louis

Mon 3/30

7:00 am-9:31 am

Nonstop4h 31m

$269

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sat 4/25

6:00 pm-11:55 pm

Nonstop3h 55m

Lambert-St Louis

Tue 4/28

7:00 am-9:31 am

Nonstop4h 31m

$269

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Tue 4/21

8:00 am-2:11 pm

Nonstop4h 11m

Lambert-St Louis

Wed 4/29

2:55 pm-5:22 pm

Nonstop4h 27m

$269

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/13

Showing 1-10 of 21 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 December 12, 2025.

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, July is the cheapest month in which you can book a flight from Seattle to St. Charles (average of $162). Flying from Seattle to St. Charles in December is currently the most expensive (average of $287). 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 December 15, 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.

Weekly flight availability from Seattle to St. Charles

Explore weekly flight availability from Seattle to St. Charles. 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 December 15, 2025.

The most flights from SEA to CH5 are scheduled on a Monday (11 on average). You will have fewer flight options on Wednesday, which is when the least amount of flights are scheduled (1 on average).

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 December 15, 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
11,455 reviews

Overall

8.0

Comfort

7.8

Entertainment

7.0

Food

7.1

Boarding

8.1

Crew

8.5

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
11,455 reviews
Alaska Airlines
8.0
Very good
11,455 reviews

Overall

8.0

Comfort

7.8

Entertainment

7.0

Food

7.1

Boarding

8.1

Crew

8.5

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
7.9
Good
4,250 reviews
Alaska Airlines
8.0
Very good
11,455 reviews

Overall

8.0

Comfort

7.8

Entertainment

7.0

Food

7.1

Boarding

8.1

Crew

8.5

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
8,010 reviews
Alaska Airlines
8.0
Very good
11,455 reviews

Overall

8.0

Comfort

7.8

Entertainment

7.0

Food

7.1

Boarding

8.1

Crew

8.5

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
2,819 reviews
Alaska Airlines
8.0
Very good
11,455 reviews

Overall

8.0

Comfort

7.8

Entertainment

7.0

Food

7.1

Boarding

8.1

Crew

8.5

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
11,050 reviews
Alaska Airlines
8.0
Very good
11,455 reviews

Overall

8.0

Comfort

7.8

Entertainment

7.0

Food

7.1

Boarding

8.1

Crew

8.5

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 are 6 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 Alaska Airlines, Delta, and United Airlines fly from Seattle to St. Charles in about 3h 59m. The time it takes to get you to your destination can typically vary by up to 5h 04m. 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. Frontier flights start at $86 while deals on American Airlines 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 Hawaiian Airlines (90%), Air Tahiti Nui (90%) and Qatar Airways (81%).

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

    On average you can expect to pay $458 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 $177.

  • 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 $162). Flying from Seattle to St. Charles in December is currently the most expensive (average of $287). 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 December 15, 2025.
AirlineCheapestAverageFlexibilityOn-time
DeltaCheapest$123Average$264FlexibilityNo cancel feeOn-timeN/A
FrontierCheapest$136Average$285FlexibilityNo cancel feeOn-time62%
SouthwestCheapest$182Average$336FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$188Average$528FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$216Average$340FlexibilityNo cancel feeOn-time69%
Hawaiian AirlinesCheapest$219Average$395FlexibilityNo cancel feeOn-time85%
Alaska AirlinesCheapest$245Average$423FlexibilityNo cancel feeOn-time75%

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