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Cheap flights from Seattle to St. Louis

SEA — STL
17 Oct — 24 Oct1
1 adult
1 adult, Economy

Cheap flight deals from Seattle to St. Louis

Discover tips and strategies to find the most affordable flight options for your journey from Seattle (SEA) to St. Louis (STL). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated 17 September 2025.

Popular in

December

Cheapest in

October

Average price

C$ 509

Good round-trip deal

C$ 394 or less
Highest demand for flights based on searches. 5% potential increase in price (C$ 42 potential increase over avg. RT price).
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Cheapest flight prices on average. 1% potential price decrease (C$ 13 potential savings vs. average RT price).
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Average for round-trip flights in September 2025
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Price to beat on a round-trip flight from Seattle/Tacoma Intl to Lambert-St Louis.
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Best time to book a flight from Seattle to St. Louis

Have a flexible travel schedule? Discover the best time to fly to St. Louis 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. Louis

How far ahead should I book a flight from Seattle to St. Louis?

Use this chart to determine the optimal time to book a round-trip flight from Seattle to St. Louis. Price data was last updated on 12 September 2025.

The price you pay for your flight from Seattle to St. Louis may vary depending on when you book. For the best chance of a lower fare, look to book 57 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.

What is the cheapest month to book a flight from Seattle to St. Louis?

Currently, January is the cheapest month in which you can book a flight from Seattle to St. Louis (average of C$ 365). Flying from Seattle to St. Louis in September is currently the most expensive (average of C$ 491). 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 STL?

Find hourly flight availability from Seattle to St. Louis. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated 17 September 2025.

A simple way to save on the total cost of your ticket is to fly from Seattle to St. Louis in the afternoon. If you’re flexible enough to do this you can expect to save up to 37% on your trip compared to booking a flight at noon.

Related info for your journey

Find useful and relevant information for your journey from Seattle to St. Louis. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • How popular is this Seattle to St. Louis flight route?

    Flights from Seattle/Tacoma Intl to Lambert-St Louis have been viewed 5 times in the past calendar month.

  • What are the most reliable airlines from Seattle to St. Louis?

    The top 3 most reliable airlines when flying from Seattle to St. Louis are Alaska Airlines (76%), Hawaiian Airlines (76%) and American Airlines (68%).

  • Can I find deals for flights from Seattle to St. Louis that include hotel bookings?

    Yes. In addition to deals on Seattle to St. Louis flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Seattle to St. Louis?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Seattle to St. Louis.

  • Can I find deals for business class flights from Seattle to St. Louis?

    Yes. Cheapflights offers flight deals from Seattle to St. Louis 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. Louis?

    Currently, January is the cheapest month in which you can book a flight from Seattle to St. Louis (average of C$ 365). Flying from Seattle to St. Louis in September is currently the most expensive (average of C$ 491). 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

Travelling to a place near St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
Chesterfield
St. Peters

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Users can book flights with no change fees policies with our dedicated filters. Book flights from Seattle to St. Louis flexibly with Cheapflights today.

Can Cheapflights notify me if prices for flights from Seattle to St. Louis become cheaper?

Yes! Start tracking prices for Seattle to St. Louis flights today and get alerted whenever prices for these flights change. To access this feature, click the bell icon next to the flight deals above, which will prompt you for a valid email address to receive your alerts.

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