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St. Charles

$77+ 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 5/6. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — STL
Mar 14 — Mar 211
Sat 3/14
Sat 3/21
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 October, booked 68 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 February 12, 2026.

This Kiwi.com deal was found by Cheapflights users on 2/10. 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.
Wed 4/226:57 pm
SEA
-
STL
1 stop22h 15m
Frontier
Mon 4/278:12 pm
STL
-
SEA
1 stop15h 15m
Frontier
Deal found 2/10$147
This Kiwi.com deal was found by Cheapflights users on 2/9. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/226:57 pm
SEA
-
STL
1 stop22h 15m
Frontier
Fri 5/18:12 pm
STL
-
SEA
1 stop15h 15m
Frontier
Deal found 2/9$154
This American Airlines deal was found by Cheapflights users on 2/9. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 3/101:37 pm
SEA
-
STL
1 stop8h 07m
American Airlines
Tue 3/176:37 pm
STL
-
SEA
1 stop7h 47m
American Airlines
Deal found 2/9$159
This Kiwi.com deal was found by Cheapflights users on 2/8. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/186:57 pm
SEA
-
STL
1 stop22h 15m
Frontier
Fri 5/18:12 pm
STL
-
SEA
1 stop15h 15m
Frontier
Deal found 2/8$161
This Kiwi.com deal was found by Cheapflights users on 2/10. 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.
Wed 5/136:57 pm
SEA
-
STL
1 stop22h 15m
Frontier
Mon 5/188:12 pm
STL
-
SEA
1 stop15h 15m
Frontier
Deal found 2/10$164
This American Airlines deal was found by Cheapflights users on 2/9. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 3/35:37 am
SEA
-
STL
1 stop7h 51m
American Airlines
Thu 3/56:50 pm
STL
-
SEA
1 stop8h 05m
American Airlines
Deal found 2/9$168
This Kiwi.com deal was found by Cheapflights users on 2/9. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/226:57 pm
SEA
-
STL
1 stop22h 15m
Frontier
Thu 4/308:12 pm
STL
-
SEA
1 stop20h 53m
Frontier
Deal found 2/9$171
This Delta deal was found by Cheapflights users on 2/8. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 4/191:30 pm
SEA
-
STL
1 stop8h 55m
Delta
Wed 4/292:20 pm
STL
-
SEA
1 stop6h 10m
Delta
Deal found 2/8$177
This Kiwi.com deal was found by Cheapflights users on 2/10. 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 5/76:57 pm
SEA
-
STL
1 stop22h 15m
Frontier
Sat 5/98:12 pm
STL
-
SEA
1 stop15h 15m
Frontier
Deal found 2/10$179
This American Airlines deal was found by Cheapflights users on 2/9. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 4/2712:59 am
SEA
-
STL
1 stop8h 38m
American Airlines
Tue 5/55:21 pm
STL
-
SEA
1 stop9h 09m
American Airlines
Deal found 2/9$184
This Delta deal was found by Cheapflights users on 2/9. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 4/209:50 am
SEA
-
STL
1 stop5h 36m
Delta
Fri 4/246:45 pm
STL
-
SEA
1 stop7h 14m
Delta
Deal found 2/9$187

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 February 12, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$147
(Kiwi.com)

One-way from

$77
(Kiwi.com)

Popular in

December

Cheapest in

January

Average price

$339
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 ($10 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($14 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in February 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 February 12, 2026.
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

Wed 4/15

3:35 pm-11:14 pm

1 stop5h 39m

Lambert-St Louis

Sun 4/19

6:45 pm-11:59 pm

1 stop7h 14m

$177

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Tue 4/21

11:14 pm-9:42 am

1 stop8h 28m

Lambert-St Louis

Fri 5/1

6:45 pm-11:59 pm

1 stop7h 14m

$177

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sat 4/18

6:00 am-4:42 pm

1 stop8h 42m

Lambert-St Louis

Tue 4/28

6:45 pm-11:59 pm

1 stop7h 14m

$177

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Mon 4/20

4:36 pm-12:25 am

1 stop5h 49m

Lambert-St Louis

Tue 4/28

6:45 pm-11:59 pm

1 stop7h 14m

$187

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sat 4/18

6:00 am-4:42 pm

1 stop8h 42m

Lambert-St Louis

Fri 5/1

6:45 pm-11:59 pm

1 stop7h 14m

$187

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Mon 4/20

4:36 pm-12:25 am

1 stop5h 49m

Lambert-St Louis

Thu 4/30

2:20 pm-6:30 pm

1 stop6h 10m

$187

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sun 4/19

1:30 pm-12:25 am

1 stop8h 55m

Lambert-St Louis

Thu 4/30

2:20 pm-6:30 pm

1 stop6h 10m

$187

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Sun 4/19

1:30 pm-12:25 am

1 stop8h 55m

Lambert-St Louis

Wed 4/29

2:20 pm-6:30 pm

1 stop6h 10m

$187

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Wed 4/22

6:00 am-4:50 pm

1 stop8h 50m

Lambert-St Louis

Wed 4/29

6:45 pm-11:59 pm

1 stop7h 14m

$187

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Thu 3/26

1:32 pm-12:21 am

1 stop8h 49m

Lambert-St Louis

Thu 4/2

2:12 pm-6:30 pm

1 stop6h 18m

$198

Flights are sorted by cheapest round-trip flights first.

Deals found on 2/9

Showing 1-10 of 23 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 February 6, 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 February 12, 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.

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 February 12, 2026.
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
11,878 reviews

Comfort

7.8

Boarding

8.1

Overall

8.0

Food

7.1

Entertainment

7.0

Crew

8.5

Reviews

1 / 20
4.0
Okay

Anonymous,Dec 2025

SEA - MSY

I really got a lesson in upgrades. I let my seat get chosen . Both times a middle seat...on purpose ...even when we were not full. That's petty I sat behind the first class . They got more than 1 drink ...and a snack . .and the staff actually talked to them...behind a see thru shawl/sheet in the aisle....... You could see over the seats just fine and you could hear the voices just fine. But the sheet let You KNOW. Your not welcome here. For a moment I regretted not spending 300 dollars per seat so I could see a smile and eat a sandwhich and enjoy my seat . The married couple drank champain and laughed and flirted with each other. It looked so happy and care free MONEY really does buy happiness ..the hateful glares and sighs from my seat mates brought me back to reality I wasn't rich and I still had 2 hours left in this middle seat.
Alaska Airlines
8.0
Very good
11,878 reviews
Alaska Airlines
8.0
Very good
11,878 reviews

Comfort

7.8

Boarding

8.1

Overall

8.0

Food

7.1

Entertainment

7.0

Crew

8.5

Reviews

1 / 20
4.0
Okay

Anonymous,Dec 2025

SEA - MSY

I really got a lesson in upgrades. I let my seat get chosen . Both times a middle seat...on purpose ...even when we were not full. That's petty I sat behind the first class . They got more than 1 drink ...and a snack . .and the staff actually talked to them...behind a see thru shawl/sheet in the aisle....... You could see over the seats just fine and you could hear the voices just fine. But the sheet let You KNOW. Your not welcome here. For a moment I regretted not spending 300 dollars per seat so I could see a smile and eat a sandwhich and enjoy my seat . The married couple drank champain and laughed and flirted with each other. It looked so happy and care free MONEY really does buy happiness ..the hateful glares and sighs from my seat mates brought me back to reality I wasn't rich and I still had 2 hours left in this middle seat.
Southwest
8.0
Very good
4,280 reviews
Alaska Airlines
8.0
Very good
11,878 reviews

Comfort

7.8

Boarding

8.1

Overall

8.0

Food

7.1

Entertainment

7.0

Crew

8.5

Reviews

1 / 20
4.0
Okay

Anonymous,Dec 2025

SEA - MSY

I really got a lesson in upgrades. I let my seat get chosen . Both times a middle seat...on purpose ...even when we were not full. That's petty I sat behind the first class . They got more than 1 drink ...and a snack . .and the staff actually talked to them...behind a see thru shawl/sheet in the aisle....... You could see over the seats just fine and you could hear the voices just fine. But the sheet let You KNOW. Your not welcome here. For a moment I regretted not spending 300 dollars per seat so I could see a smile and eat a sandwhich and enjoy my seat . The married couple drank champain and laughed and flirted with each other. It looked so happy and care free MONEY really does buy happiness ..the hateful glares and sighs from my seat mates brought me back to reality I wasn't rich and I still had 2 hours left in this middle seat.
Delta
7.9
Good
8,181 reviews
Alaska Airlines
8.0
Very good
11,878 reviews

Comfort

7.8

Boarding

8.1

Overall

8.0

Food

7.1

Entertainment

7.0

Crew

8.5

Reviews

1 / 20
4.0
Okay

Anonymous,Dec 2025

SEA - MSY

I really got a lesson in upgrades. I let my seat get chosen . Both times a middle seat...on purpose ...even when we were not full. That's petty I sat behind the first class . They got more than 1 drink ...and a snack . .and the staff actually talked to them...behind a see thru shawl/sheet in the aisle....... You could see over the seats just fine and you could hear the voices just fine. But the sheet let You KNOW. Your not welcome here. For a moment I regretted not spending 300 dollars per seat so I could see a smile and eat a sandwhich and enjoy my seat . The married couple drank champain and laughed and flirted with each other. It looked so happy and care free MONEY really does buy happiness ..the hateful glares and sighs from my seat mates brought me back to reality I wasn't rich and I still had 2 hours left in this middle seat.
Hawaiian Airlines
7.8
Good
2,833 reviews
Alaska Airlines
8.0
Very good
11,878 reviews

Comfort

7.8

Boarding

8.1

Overall

8.0

Food

7.1

Entertainment

7.0

Crew

8.5

Reviews

1 / 20
4.0
Okay

Anonymous,Dec 2025

SEA - MSY

I really got a lesson in upgrades. I let my seat get chosen . Both times a middle seat...on purpose ...even when we were not full. That's petty I sat behind the first class . They got more than 1 drink ...and a snack . .and the staff actually talked to them...behind a see thru shawl/sheet in the aisle....... You could see over the seats just fine and you could hear the voices just fine. But the sheet let You KNOW. Your not welcome here. For a moment I regretted not spending 300 dollars per seat so I could see a smile and eat a sandwhich and enjoy my seat . The married couple drank champain and laughed and flirted with each other. It looked so happy and care free MONEY really does buy happiness ..the hateful glares and sighs from my seat mates brought me back to reality I wasn't rich and I still had 2 hours left in this middle seat.
American Airlines
7.2
Good
11,271 reviews
Alaska Airlines
8.0
Very good
11,878 reviews

Comfort

7.8

Boarding

8.1

Overall

8.0

Food

7.1

Entertainment

7.0

Crew

8.5

Reviews

1 / 20
4.0
Okay

Anonymous,Dec 2025

SEA - MSY

I really got a lesson in upgrades. I let my seat get chosen . Both times a middle seat...on purpose ...even when we were not full. That's petty I sat behind the first class . They got more than 1 drink ...and a snack . .and the staff actually talked to them...behind a see thru shawl/sheet in the aisle....... You could see over the seats just fine and you could hear the voices just fine. But the sheet let You KNOW. Your not welcome here. For a moment I regretted not spending 300 dollars per seat so I could see a smile and eat a sandwhich and enjoy my seat . The married couple drank champain and laughed and flirted with each other. It looked so happy and care free MONEY really does buy happiness ..the hateful glares and sighs from my seat mates brought me back to reality I wasn't rich and I still had 2 hours left in this middle seat.

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 4 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 Delta fly from Seattle to St. Charles in about 8h 28m. The time it takes to get you to your destination can typically vary by up to . The distance from Seattle to St. Charles is about 1704 mi.

  • 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 Frontier 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 Qatar Airways (93%), Alaska Airlines (89%) and Hawaiian Airlines (89%).

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

    On average you can expect to pay $268 for a flight from Seattle to St. Charles. The cheapest flight overall is $98 while the most popular route, (Seattle/Tacoma Intl - Lambert-St Louis) is currently priced at $209.

  • 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

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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 February 12, 2026.
AirlineCheapestAverageFlexibilityOn-time
DeltaCheapest$94Average$245FlexibilityNo cancel feeOn-timeN/A
FrontierCheapest$136Average$228FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$157Average$303FlexibilityNo cancel feeOn-time69%
Hawaiian AirlinesCheapest$181Average$386FlexibilityNo cancel feeOn-time85%
SouthwestCheapest$182Average$319FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$188Average$525FlexibilityNo cancel feeOn-time71%
Alaska AirlinesCheapest$227Average$400FlexibilityNo cancel feeOn-time75%

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