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St. Charles

$88+ 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 6/1. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — STL
Jun 9 — Jun 161
Tue 6/9
Tue 6/16
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 77 days in advance, depart on a Tuesday or Thursday 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 May 10, 2026.

This Booking.com deal was found by Cheapflights users on 5/7. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/238:12 pm
SEA
-
STL
1 stop20h 39m
Frontier
Fri 6/262:56 pm
STL
-
SEA
1 stop21h 39m
Frontier
Deal found 5/7$297
This CheapOair deal was found by Cheapflights users on 5/9. 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 5/258:20 pm
SEA
-
STL
1 stop19h 46m
Frontier
Fri 5/298:08 pm
STL
-
SEA
1 stop15h 58m
Frontier
Deal found 5/9$300
This Mytrip deal was found by Cheapflights users on 5/7. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 6/187:41 pm
SEA
-
STL
1 stop21h 12m
Frontier
Sun 6/212:56 pm
STL
-
SEA
1 stop21h 39m
Frontier
Deal found 5/7$301
This Kiwi.com deal was found by Cheapflights users on 5/7. 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 6/17:50 pm
SEA
-
STL
1 stop21h 33m
Frontier
Fri 6/55:27 pm
STL
-
SEA
2 stops27h 08m
Frontier
Deal found 5/7$304
This Kiwi.com deal was found by Cheapflights users on 5/6. 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.
Sat 7/118:12 pm
SEA
-
STL
2 stops19h 25m
Frontier
Tue 7/148:08 pm
STL
-
SEA
1 stop15h 41m
Frontier
Deal found 5/6$307
This CheapOair deal was found by Cheapflights users on 5/8. 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.
Wed 5/207:50 pm
SEA
-
STL
1 stop21h 33m
Frontier
Wed 5/278:08 pm
STL
-
SEA
1 stop15h 58m
Frontier
Deal found 5/8$310
This United Airlines deal was found by Cheapflights users on 5/5. 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.
Thu 8/272:26 pm
SEA
-
STL
1 stop7h 24m
United Airlines
Mon 8/314:40 pm
STL
-
SEA
1 stop6h 31m
United Airlines
Deal found 5/5$312
This Kiwi.com deal was found by Cheapflights users on 5/7. 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 6/167:41 pm
SEA
-
STL
1 stop21h 42m
Frontier
Tue 6/237:03 pm
STL
-
SEA
2 stops17h 32m
Frontier
Deal found 5/7$313
This Kiwi.com deal was found by Cheapflights users on 5/6. 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 7/103:34 pm
SEA
-
STL
2 stops15h 23m
Frontier
Tue 7/148:08 pm
STL
-
SEA
1 stop15h 41m
Frontier
Deal found 5/6$314
This United Airlines deal was found by Cheapflights users on 5/5. 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.
Wed 6/103:40 pm
SEA
-
STL
1 stop6h 17m
United Airlines
Sat 6/137:23 pm
STL
-
SEA
1 stop7h 50m
United Airlines
Deal found 5/5$315
This Booking.com deal was found by Cheapflights users on 5/7. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/238:12 pm
SEA
-
STL
1 stop20h 39m
Frontier
Sat 6/277:38 pm
STL
-
SEA
1 stop20h 40m
Frontier
Deal found 5/7$316
This Alaska Airlines deal was found by Cheapflights users on 5/7. 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 6/312:45 pm
SEA
-
STL
Nonstop4h 00m
Alaska Airlines
Sat 6/67:41 pm
STL
-
SEA
Nonstop4h 30m
Alaska Airlines
Deal found 5/7$317

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 May 10, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$297
(Booking.com)

One-way from

$88
(Kiwi.com)

Popular in

December

Cheapest in

January

Average price

$432
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. 2% potential increase in price ($8 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 May 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 May 10, 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
Quickest round-trip

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sat 5/30

5:52 pm-11:54 pm

Nonstop4h 02m

Lambert-St Louis

Sat 6/6

4:12 pm-6:41 pm

Nonstop4h 29m

$317

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Fri 6/5

9:00 am-2:50 pm

Nonstop3h 50m

Lambert-St Louis

Tue 6/9

6:55 pm-12:30 am

1 stop7h 35m

$357

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Thu 6/11

5:20 pm-1:50 am

1 stop6h 30m

Lambert-St Louis

Tue 6/16

12:10 pm-2:25 pm

Nonstop4h 15m

$383

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sat 7/11

6:45 am-6:00 pm

2 stops9h 15m

Lambert-St Louis

Sun 7/12

7:35 pm-1:10 am

1 stop7h 35m

$392

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Thu 5/28

12:55 pm-12:15 am

2 stops9h 20m

Lambert-St Louis

Mon 6/1

4:40 pm-12:05 am

1 stop9h 25m

$402

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Tue 6/30

6:04 pm-11:59 pm

Nonstop3h 55m

Lambert-St Louis

Sat 7/4

5:37 pm-5:53 am

1 stop14h 16m

$467

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sat 6/13

6:42 am-4:37 pm

1 stop7h 55m

Lambert-St Louis

Sat 6/20

7:56 pm-10:24 pm

Nonstop4h 28m

$537

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Wed 8/5

8:35 am-8:43 pm

2 stops10h 08m

Lambert-St Louis

Sun 8/9

9:15 am-4:09 pm

1 stop8h 54m

$573

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Tue 6/30

8:35 am-8:43 pm

2 stops10h 08m

Lambert-St Louis

Sat 7/4

7:23 pm-1:13 am

1 stop7h 50m

$589

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Fri 6/26

10:29 am-11:57 pm

2 stops11h 28m

Lambert-St Louis

Mon 6/29

5:10 am-10:00 am

1 stop6h 50m

$624

Flights are sorted by cheapest round-trip flights first.

Deals found on 5/7

Showing 1-10 of 23 resultsSorted by cheapest first
1
2
3

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

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 May 10, 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 May 10, 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
4,304 reviews

Crew

8.6

Boarding

8.1

Entertainment

7.5

Comfort

8.0

Overall

8.0

Food

7.0

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
4,304 reviews
Southwest
8.0
Very good
4,304 reviews

Crew

8.6

Boarding

8.1

Entertainment

7.5

Comfort

8.0

Overall

8.0

Food

7.0

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
12,348 reviews
Southwest
8.0
Very good
4,304 reviews

Crew

8.6

Boarding

8.1

Entertainment

7.5

Comfort

8.0

Overall

8.0

Food

7.0

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
8,455 reviews
Southwest
8.0
Very good
4,304 reviews

Crew

8.6

Boarding

8.1

Entertainment

7.5

Comfort

8.0

Overall

8.0

Food

7.0

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
4,304 reviews

Crew

8.6

Boarding

8.1

Entertainment

7.5

Comfort

8.0

Overall

8.0

Food

7.0

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
11,667 reviews
Southwest
8.0
Very good
4,304 reviews

Crew

8.6

Boarding

8.1

Entertainment

7.5

Comfort

8.0

Overall

8.0

Food

7.0

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 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 Alaska Airlines and Southwest fly from Seattle to St. Charles in about 3h 50m. The time it takes to get you to your destination is usually consistent. The distance from Seattle to St. Charles is about 1704 mi. All flights are typically nonstop.

  • 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. Southwest flights start at $84 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 American Airlines (97%), Alaska Airlines (97%) and Hawaiian Airlines (97%).

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

    On average you can expect to pay $390 for a flight from Seattle to St. Charles. The cheapest flight overall is $158 while the most popular route, (Seattle/Tacoma Intl - Lambert-St Louis) is currently priced at $260.

  • 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.

See more FAQs

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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 May 10, 2026.
AirlineCheapestAverageFlexibilityOn-time
DeltaCheapest$94Average$308FlexibilityNo cancel feeOn-timeN/A
FrontierCheapest$136Average$218FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$157Average$348FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$182Average$364FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$188Average$488FlexibilityNo cancel feeOn-time71%
Hawaiian AirlinesCheapest$217Average$384FlexibilityNo cancel feeOn-time85%
Alaska AirlinesCheapest$226Average$413FlexibilityNo cancel feeOn-time75%

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