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St. Charles

$83+ 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 10/13. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — STL
Oct 15 — Oct 221
Wed 10/15
Wed 10/22
1 adult, Economy
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Cheapflights Tip: The best prices from Seattle/Tacoma Intl to St. Charles are usually found in October or June, booked 57 days in advance, depart on a Thursday or Monday 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 September 15, 2025.

Round-trip from

$188
(Frontier)

One-way from

$83
(Trip.com)

Popular in

December

Cheapest in

October

Average price

$370
From Seattle/Tacoma Intl to St. Charles
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One-way flight from Seattle/Tacoma Intl to St. Charles
Search Deals
Highest demand for flights based on searches. 5% potential increase in price ($21 potential increase over avg. RT price).
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Cheapest flight prices on average. 1% potential price decrease ($7 potential savings vs. average RT price).
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Average for round-trip flights in September 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 September 15, 2025.

This Frontier deal was found by Cheapflights users on 9/14. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/294:36 pmSEA - STL
2 stops14h 30mFrontier
Fri 10/37:55 pmSTL - SEA
1 stop6h 35mFrontier
Deal found 9/14$188
This Kiwi.com deal was found by Cheapflights users on 9/15. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/231:02 pmSEA - STL
1 stop18h 05mFrontier
Mon 10/277:52 pmSTL - SEA
1 stop18h 21mFrontier
Deal found 9/15$194
This Trip.com deal was found by Cheapflights users on 9/14. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/36:12 amSEA - STL
1 stop24h 54mFrontier
Sun 10/57:55 pmSTL - SEA
1 stop6h 35mFrontier
Deal found 9/14$195
This Kiwi.com deal was found by Cheapflights users on 9/15. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/138:43 pmSEA - STL
1 stop10h 24mFrontier
Mon 10/207:52 pmSTL - SEA
1 stop18h 15mFrontier
Deal found 9/15$197
This Kiwi.com deal was found by Cheapflights users on 9/14. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 11/162:22 pmSEA - STL
1 stop16h 45mFrontier
Tue 11/187:45 pmSTL - SEA
1 stop18h 28mFrontier
Deal found 9/14$199
This Frontier deal was found by Cheapflights users on 9/15. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/208:43 pmSEA - STL
1 stop10h 24mFrontier
Thu 10/231:41 pmSTL - SEA
2 stops19h 52mFrontier
Deal found 9/15$201
This Southwest deal was found by Cheapflights users on 9/15. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/115:45 amSEA - STL
1 stop9h 15mSouthwest
Sat 10/183:35 pmSTL - SEA
1 stop8h 10mSouthwest
Deal found 9/15$202
This Delta deal was found by Cheapflights users on 9/15. 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.
Sat 11/156:00 amSEA - STL
1 stop8h 49mDelta
Sun 11/232:36 pmSTL - SEA
1 stop9h 38mDelta
Deal found 9/15$203
This Kiwi.com deal was found by Cheapflights users on 9/14. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/1710:16 amSEA - STL
2 stops20h 51mFrontier
Tue 10/217:52 pmSTL - SEA
1 stop18h 15mFrontier
Deal found 9/14$204
This Southwest deal was found by Cheapflights users on 9/15. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/235:15 amSEA - STL
1 stop7h 40mSouthwest
Thu 10/235:45 pmSTL - SEA
1 stop7h 00mSouthwest
Deal found 9/15$209
This Trip.com deal was found by Cheapflights users on 9/13. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/307:00 amSEA - STL
1 stop24h 06mMultiple Airlines
Tue 10/76:33 amSTL - SEA
Nonstop4h 32mMultiple Airlines
Deal found 9/13$210

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 September 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

Sat 10/11

5:45 am-5:00 pm

1 stop9h 15m

Lambert-St Louis

Sat 10/18

3:35 pm-9:45 pm

1 stop8h 10m

$202

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sat 11/15

6:00 am-5:23 pm

1 stop9h 23m

Lambert-St Louis

Mon 11/17

2:36 pm-10:14 pm

1 stop9h 38m

$203

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Wed 12/10

6:00 am-5:09 pm

1 stop9h 09m

Lambert-St Louis

Sun 12/14

6:00 am-10:54 am

1 stop6h 54m

$203

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Fri 11/7

11:55 pm-8:51 am

1 stop6h 56m

Lambert-St Louis

Tue 11/11

6:50 am-12:56 pm

1 stop8h 06m

$203

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Fri 11/7

11:55 pm-8:51 am

1 stop6h 56m

Lambert-St Louis

Mon 11/10

5:34 pm-11:59 pm

1 stop8h 25m

$209

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sat 11/15

7:00 am-3:46 pm

1 stop6h 46m

Lambert-St Louis

Mon 11/17

3:14 pm-11:10 pm

2 stops9h 56m

$218

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Tue 9/30

10:45 pm-7:35 am

1 stop6h 50m

Lambert-St Louis

Tue 10/7

3:00 pm-10:00 pm

2 stops9h 00m

$237

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sat 11/15

9:15 am-3:18 pm

Nonstop4h 03m

Lambert-St Louis

Sun 11/23

7:00 am-9:41 am

Nonstop4h 41m

$247

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sat 11/15

9:15 am-3:18 pm

Nonstop4h 03m

Lambert-St Louis

Mon 11/17

4:14 pm-6:48 pm

Nonstop4h 34m

$247

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sun 10/26

8:43 pm-9:07 am

1 stop10h 24m

$85

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/15

Showing 1-10 of 20 results
1
2

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 September 12, 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, August is the cheapest month in which you can book a flight from Seattle to St. Charles (average of $311). Flying from Seattle to St. Charles in March is currently the most expensive (average of $356). 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 September 15, 2025.

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.

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 Tuesday evenings when fares are most often at their lowest. Monday 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 September 15, 2025.

The most flights from SEA to CH5 are scheduled on a Monday (16 on average). You will have fewer flight options on Wednesday, which is when the least amount of flights are scheduled (3 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 September 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
10,000 reviews

Entertainment

7.0

Boarding

8.1

Crew

8.5

Food

7.1

Overall

8.0

Comfort

7.8

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
Alaska Airlines
8.0
Very good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.0

Boarding

8.1

Crew

8.5

Food

7.1

Overall

8.0

Comfort

7.8

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
Southwest
8.0
Very good
4,242 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.0

Boarding

8.1

Crew

8.5

Food

7.1

Overall

8.0

Comfort

7.8

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
Delta
8.0
Very good
7,954 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.0

Boarding

8.1

Crew

8.5

Food

7.1

Overall

8.0

Comfort

7.8

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
Hawaiian Airlines
7.8
Good
2,723 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.0

Boarding

8.1

Crew

8.5

Food

7.1

Overall

8.0

Comfort

7.8

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
American Airlines
7.2
Good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.0

Boarding

8.1

Crew

8.5

Food

7.1

Overall

8.0

Comfort

7.8

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.

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 12 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 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 and Delta fly from Seattle to St. Charles in about 9h 15m. The time it takes to get you to your destination can typically vary by up to 08m. 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 Alaska Airlines (75%), Hawaiian Airlines (75%) and Air Tahiti Nui (69%).

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

    On average you can expect to pay $534 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 $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, August is the cheapest month in which you can book a flight from Seattle to St. Charles (average of $311). Flying from Seattle to St. Charles in March is currently the most expensive (average of $356). 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 September 15, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$137Average$286FlexibilityNo cancel feeOn-time62%
DeltaCheapest$176Average$300FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$186Average$542FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$188Average$388FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$216Average$380FlexibilityNo cancel feeOn-time69%
Hawaiian AirlinesCheapest$219Average$393FlexibilityNo cancel feeOn-time85%
Alaska AirlinesCheapest$246Average$423FlexibilityNo cancel feeOn-time75%

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