$229 Cheap Flights from St. Louis (STL) to Watertown (ATY)

View $229 flight on Tue, Jan 6, 2026Opens in a new window

Popular airlines from St. Louis Lambert Intl. Airport (STL) to Watertown, SD (ATY-Watertown Regional)

Cheap Flights from St. Louis to Watertown (STL-ATY)

Prices were available within the past 7 days and start at $229 for one-way flights and $234 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Delta
Tue, Jan 6 - Sun, Jan 11
STL
St. Louis
ATY
Watertown
$234 Roundtrip, found 1 day ago
$234
Roundtrip
found 1 day ago
Select Delta flight, departing Tue, Jan 6 from St. Louis to Watertown, returning Sun, Jan 11, priced at $234 found 1 day ago
Delta
Mon, Nov 24 - Fri, Nov 28
STL
St. Louis
ATY
Watertown
$249 Roundtrip, found 2 days ago
$249
Roundtrip
found 2 days ago
Select Delta flight, departing Mon, Nov 24 from St. Louis to Watertown, returning Fri, Nov 28, priced at $249 found 2 days ago
Delta
Mon, Nov 24 - Tue, Dec 2
STL
St. Louis
ATY
Watertown
$259 Roundtrip, found 2 days ago
$259
Roundtrip
found 2 days ago
Select Delta flight, departing Mon, Nov 24 from St. Louis to Watertown, returning Tue, Dec 2, priced at $259 found 2 days ago
Delta
Tue, Jan 6 - Sun, Jan 11
STL
St. Louis
ATY
Watertown
$304 Roundtrip, found 1 day ago
$304
Roundtrip
found 1 day ago
Select Delta flight, departing Tue, Jan 6 from St. Louis to Watertown, returning Sun, Jan 11, priced at $304 found 1 day ago
Delta
Wed, Nov 19 - Mon, Nov 24
STL
St. Louis
ATY
Watertown
$329 Roundtrip, found 4 days ago
$329
Roundtrip
found 4 days ago
Select Delta flight, departing Wed, Nov 19 from St. Louis to Watertown, returning Mon, Nov 24, priced at $329 found 4 days ago
Delta
Fri, Nov 28 - Tue, Dec 2
STL
St. Louis
ATY
Watertown
$339 Roundtrip, found 2 days ago
$339
Roundtrip
found 2 days ago
Select Delta flight, departing Fri, Nov 28 from St. Louis to Watertown, returning Tue, Dec 2, priced at $339 found 2 days ago
Delta
Tue, Jan 6 - Sun, Jan 11
STL
St. Louis
ATY
Watertown
$364 Roundtrip, found 1 day ago
$364
Roundtrip
found 1 day ago
Select Delta flight, departing Tue, Jan 6 from St. Louis to Watertown, returning Sun, Jan 11, priced at $364 found 1 day ago
Delta
Wed, Nov 19 - Mon, Nov 24
STL
St. Louis
ATY
Watertown
$389 Roundtrip, found 4 days ago
$389
Roundtrip
found 4 days ago
Select Delta flight, departing Wed, Nov 19 from St. Louis to Watertown, returning Mon, Nov 24, priced at $389 found 4 days ago
Delta
Wed, Nov 26 - Fri, Nov 28
STL
St. Louis
ATY
Watertown
$434 Roundtrip, found 2 days ago
$434
Roundtrip
found 2 days ago
Select Delta flight, departing Wed, Nov 26 from St. Louis to Watertown, returning Fri, Nov 28, priced at $434 found 2 days ago
United
Tue, Jan 6 - Sun, Jan 11
STL
St. Louis
ATY
Watertown
$466 Roundtrip, found 1 day ago
$466
Roundtrip
found 1 day ago
Select United flight, departing Tue, Jan 6 from St. Louis to Watertown, returning Sun, Jan 11, priced at $466 found 1 day ago

Frequently asked questions

How much does a flight from Lambert-St. Louis Intl. Airport (STL) to Watertown Regional Airport (ATY) cost?
Lock in a cheap one-way flight from $229 or cheap return flight from $234 from Lambert-St. Louis Intl. Airport (STL) to Watertown Regional Airport (ATY) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to find our cheapest flight deals on this route.
What is the cheapest month to fly from Lambert-St. Louis Intl. Airport (STL) to Watertown Regional Airport (ATY)?
Traveling in January can help you save, as it's the cheapest month for flights between STL and ATY. You'll typically find the lowest prices during the off-season.
What is the cheapest airline that flies from Lambert-St. Louis Intl. Airport (STL) to Watertown Regional Airport (ATY)?
To find the cheapest airline that'll fly you from STL to ATY, use Expedia's filter tool. Customize your search based on your travel style, such as preferred carriers and seat class. You can then sort your results by "Price (lowest to highest)" to see the cheapest fares upfront.
How many flights per day from Lambert-St. Louis Intl. Airport (STL) to Watertown Regional Airport (ATY)?
Nonstop flights from Lambert-St. Louis Intl. Airport (STL) to Watertown Regional Airport (ATY) aren't available daily, so you'll have to take a flight with a layover. Explore your options with our filter tool. Enter your dates and pick either "1 Stop" or "2+ Stops."
What day of the week has the most flights from STL to ATY?
You'll typically find Tuesday the quietest day for flights, while Fridays tend to be the busiest.* However this can change from season to season and during peak travel times or public holidays.*Busiest/quietest day to travel is based on Expedia flight demand through January to December 2024.
What is the best time to fly from Lambert-St. Louis Intl. Airport (STL) to Watertown Regional Airport (ATY)?
To arrive at Watertown Regional Airport (ATY) without delays, select a flight that leaves Lambert-St. Louis Intl. Airport (STL) before 3 PM. The likelihood of cancellations is 22% higher, on average, for departures after this hour.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
Is it cheaper to buy a plane ticket from Lambert-St. Louis Intl. Airport (STL) to Watertown Regional Airport (ATY) last-minute?
Holding off until just before your departure to book a flight from STL to ATY generally means paying more. Although you may find some last-minute deals, they're not always guaranteed. Be flexible with your travel plans for a better chance of snagging a bargain.
Is it cheaper to book a STL to ATY flight and hotel package?
Securing a STL to ATY flight and hotel package is generally cheaper than booking separately. With Expedia, you can enjoy the convenience of organizing your travels in one place. Choose from our extensive range of hotels and then add car rentals, flights and activities to your booking. Bundle everything together, and you could save hundreds of dollars.
Can I cancel or change the date of my flight from Lambert-St. Louis Intl. Airport (STL) to Watertown Regional Airport (ATY)?
Generally, it's possible to reschedule or cancel your STL to ATY flight. However, if the booking was made more than 24 hours ago, additional charges may apply. Refer to your airline's policies in your itinerary to see what changes are possible and if any costs are involved. You'll also find more information on our Customer Service portal.

Travel information

Origin airport
Lambert-St. Louis Intl.
Destination airport
Watertown Regional
Airlines serving
Delta, United
Roundtrip price
$233
Distance
551 mi

Book with confidence

St. Louis to Watertown Flights

The cheapest times to fly from St. Louis to Watertown

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from St. Louis to Watertown are during the month of January. You can find some of the cheapest flights from St. Louis to Watertown with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from St. Louis to Watertown

Sunday is one of the best days to book for cheap flights from St. Louis to Watertown: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

 

How to find cheap round-trip tickets from St. Louis to Watertown

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from St. Louis to Watertown in 2025. You can also book with separate airlines for your outbound and return journeys, from $229 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

 

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap St. Louis to Watertown flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

 

You could also save big by booking one of Expedia's vacation packages. Bundling together your St. Louis to Watertown airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

 

*Terms apply.

 

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

 

St. Louis to Watertown Flights

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*Available to One Key members.