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Cheap flights from Ontario to St. Louis from C$ 252

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 9/6. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — STL
18 Apr — 25 Apr1
1 adult
1 adult, Economy, 0 bags

Cheap flight deals from Ontario to St. Louis

Enter your travel dates to find the best prices.

Cheapest flights from Ontario to St. Louis
Explore the most affordable flight options available from Ontario to St. Louis. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 19 March 2026.

Tue 5/57:00 a.m.
YOW
-
STL
1 stop6h 06m
Air Canada
Wed 6/51:05 p.m.
STL
-
YOW
1 stop6h 46m
Air Canada
Deal found 18/3C$ 410
Fri 5/67:00 a.m.
YOW
-
STL
1 stop6h 06m
Air Canada
Sun 7/67:05 a.m.
STL
-
YOW
1 stop5h 00m
Air Canada
Deal found 18/3C$ 418
Fri 22/55:20 p.m.
YOW
-
STL
1 stop4h 56m
United Airlines
Sun 24/51:13 p.m.
STL
-
YOW
2 stops9h 41m
United Airlines
Deal found 15/3C$ 422
Sat 11/45:25 p.m.
YOW
-
STL
1 stop4h 48m
United Airlines
Sat 18/49:16 a.m.
STL
-
YOW
1 stop11h 19m
United Airlines
Deal found 14/3C$ 424
Wed 3/65:20 p.m.
YOW
-
STL
1 stop4h 56m
United Airlines
Sat 6/66:00 a.m.
STL
-
YOW
2 stops8h 11m
United Airlines
Deal found 15/3C$ 507
Tue 5/52:00 p.m.
YOW
-
STL
2 stops8h 13m
United Airlines
Wed 6/57:45 a.m.
STL
-
YOW
1 stop8h 22m
United Airlines
Deal found 18/3C$ 508
Wed 27/511:40 a.m.
YYZ
-
STL
1 stop9h 50m
American Airlines
Wed 10/61:45 p.m.
STL
-
YYZ
1 stop8h 44m
American Airlines
Deal found 18/3C$ 510
Wed 15/43:13 p.m.
YYZ
-
STL
1 stop8h 04m
American Airlines
Wed 22/48:54 a.m.
STL
-
YYZ
1 stop7h 49m
American Airlines
Deal found 18/3C$ 521
Sat 2/512:30 p.m.
YUL
-
STL
1 stop8h 39m
American Airlines
Sat 9/52:33 p.m.
STL
-
YUL
1 stop20h 11m
American Airlines
Deal found 18/3C$ 539
Mon 13/45:15 p.m.
YYZ
-
STL
2 stops38h 35m
Multiple Airlines
Mon 20/44:59 p.m.
STL
-
YYZ
1 stop20h 09m
Multiple Airlines
Deal found 16/3C$ 539
Tue 28/412:30 p.m.
YUL
-
STL
1 stop12h 16m
American Airlines
Tue 5/54:30 p.m.
STL
-
YUL
1 stop18h 14m
American Airlines
Deal found 14/3C$ 540
Tue 5/512:30 p.m.
YUL
-
STL
1 stop10h 49m
American Airlines
Sat 9/58:03 p.m.
STL
-
YUL
1 stop14h 41m
American Airlines
Deal found 15/3C$ 545

Find flight deals from Ontario to St. Louis

Keep the following information in mind while searching for Ontario to St. Louis flight deals. Data was last updated 19 March 2026.

Round-trip from

C$ 410

One-way from

C$ 252

Popular in

March

Cheapest in

June

Average price

C$ 1,268

Good round-trip deal

C$ 693 or less
Air Canada
  • Air Canada
  • 5/5-6/5
  • 2 total stops
  • 12h 52m total
  • Ontario to St. Louis
Search Deals
United Airlines
  • United Airlines
  • 9/6
  • 2 total stops
  • 17h 41m total
  • Ontario to St. Louis
Search Deals
Highest demand for flights based on searches. 20% potential increase in price (C$ 233 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 8% potential price decrease (C$ 75 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in March 2026
Search Deals
Price to beat on a round-trip flight from Ontario to Lambert-St Louis.
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Ontario to St. Louis 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 629,999 searches. Data last updated 19 March 2026.
Use the filters below to find and compare flights from Ontario to St. Louis that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Tue 5/5

7:00 a.m.-12:06 p.m.

1 stop6h 06m

Lambert-St Louis

Wed 6/5

1:05 p.m.-8:51 p.m.

1 stop6h 46m

C$ 410

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Fri 22/5

5:20 p.m.-9:16 p.m.

1 stop4h 56m

Lambert-St Louis

Sun 24/5

1:13 p.m.-9:35 p.m.

1 stop7h 22m

C$ 422

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Sat 11/4

6:00 a.m.-2:24 p.m.

2 stops9h 24m

Lambert-St Louis

Sat 18/4

9:16 a.m.-6:55 p.m.

2 stops8h 39m

C$ 424

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Wed 3/6

10:44 a.m.-3:46 p.m.

1 stop6h 02m

Lambert-St Louis

Sat 6/6

6:00 a.m.-9:35 p.m.

1 stop14h 35m

C$ 424

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Tue 5/5

2:00 p.m.-9:13 p.m.

2 stops8h 13m

Lambert-St Louis

Wed 6/5

7:45 a.m.-5:07 p.m.

1 stop8h 22m

C$ 508

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Fri 5/6

5:05 a.m.-12:11 p.m.

2 stops8h 06m

Lambert-St Louis

Sun 7/6

1:13 p.m.-9:35 p.m.

1 stop7h 22m

C$ 508

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Fri 17/4

2:45 p.m.-9:52 p.m.

1 stop8h 07m

Lambert-St Louis

Sun 19/4

6:55 p.m.-11:59 p.m.

1 stop4h 04m

C$ 602

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Thu 16/4

2:45 p.m.-9:13 p.m.

1 stop7h 28m

Lambert-St Louis

Thu 23/4

6:30 a.m.-11:49 a.m.

1 stop4h 19m

C$ 602

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Wed 29/4

1:20 p.m.-9:13 p.m.

1 stop8h 53m

Lambert-St Louis

Sat 2/5

9:00 a.m.-9:26 p.m.

1 stop11h 26m

C$ 630

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Thu 4/6

7:20 a.m.-2:06 p.m.

1 stop7h 46m

Lambert-St Louis

Mon 8/6

9:23 a.m.-6:45 p.m.

1 stop8h 22m

C$ 639

Flights are sorted by cheapest round-trip flights first.

Deals found on 16/3

Showing 1-10 of 46 resultsSorted by cheapest first
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Best time to book a flight from Ontario to St. Louis

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

What is the cheapest month to book a flight from Region of Ontario to St. Louis?

Currently, December is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of C$ 339). Flying from Region of Ontario to St. Louis in April is currently the most expensive (average of C$ 507). 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 ON to STL?

Find hourly flight availability from Ontario 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 19 March 2026.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Region of Ontario to St. Louis as you normally would.

Weekly flight availability from Region of Ontario to St. Louis

Explore weekly flight availability from Ontario to St. Louis. 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 19 March 2026.

The most flights from CAON to STL are scheduled on a Monday (2 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (2 on average).

Related info for your journey

Find useful and relevant information for your journey from Ontario to St. Louis. 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 into for flights to St. Louis from Ontario?

    Most people fly into Lambert-St Louis (STL) if they book a flight to St. Louis from Ontario. Lambert-St Louis is conveniently located just 20.4 km from St. Louis’s city centre.

  • How long is the flight from Region of Ontario to St. Louis?

    Air Canada, United Airlines, and American Airlines can get you from Region of Ontario to St. Louis in just under 4h 56m. Your travel time can differ by up to 2h 50m. The distance between Region of Ontario and St. Louis is about 1413 km. When browsing for deals, the options you’ll see will be for both direct flights and flights with stops.

  • What are the most popular routes from Region of Ontario to St. Louis?

    While some choose either Montreal Pierre Elliott Trudeau Intl - Lambert-St Louis or Ottawa - Lambert-St Louis, Toronto Pearson Intl - Lambert-St Louis is the most popular route from Region of Ontario to St. Louis.

  • What are the most reliable airlines from Region of Ontario to St. Louis?

    Consider United Airlines (72%), Air Canada (71%) or Jazz (71%) when booking your flight. These represent the most reliable airlines when flying from Region of Ontario to St. Louis.

  • What are the cheapest flights from Region of Ontario to St. Louis?

    Looking for the cheapest flight from Region of Ontario to St. Louis? While on average our users pay C$ 748, our data indicates the cheapest price to be C$ 505. The most popular route (Toronto Pearson Intl - Lambert-St Louis), is priced around C$ 539.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from Ontario 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 Region of Ontario to St. Louis?

    Currently, December is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of C$ 339). Flying from Region of Ontario to St. Louis in April is currently the most expensive (average of C$ 507). 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
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Top 5 airlines flying from Ontario to St. Louis

Discover the top 5 airlines that operate flights from Ontario to St. Louis. 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 629,999 searches. Data last updated 19 March 2026.
AirlineCheapestAverageFlexibilityOn-time
United AirlinesCheapestC$ 330AverageC$ 663FlexibilityNo cancel feeOn-time69%
Search United Airlines flights
American AirlinesCheapestC$ 362AverageC$ 680FlexibilityNo cancel feeOn-time71%
Search American Airlines flights
Air CanadaCheapestC$ 455AverageC$ 727FlexibilityNo cancel feeOn-time67%
Search Air Canada flights
DeltaCheapestC$ 471AverageC$ 641FlexibilityNo cancel feeOn-timeN/A
Search Delta flights
WestJetCheapestC$ 553AverageC$ 978FlexibilityNo cancel feeOn-time60%
Search WestJet flights

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travelers can enjoy low prices and a wide availability of flights to their desired destinations.

How does Cheapflights help users find flights from Ontario to St. Louis?

When you search for this flight from Ontario to St. Louis, Cheapflights searches on 900+ travel sites to save you time finding great flight deals online. Additionally, we offer filter features so you can choose a preferred cabin class or airline, see different price ranges, and much more so you can book the flight for you.

Why should you use Cheapflights to find cheap flight tickets from Ontario to St. Louis?

Cheapflights helps you find that perfect flight to St. Louis from Ontario by searching from hundreds of airlines and agencies you know and love. We are also free to use, in case you were wondering!

Can Cheapflights find flights from Ontario to St. Louis with no change fees?

Certainly. Search results for flights to St. Louis from Ontario shown to you on Cheapflights can be narrowed down with different useful search filters, which includes flexible booking options.

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

Yes! Start tracking prices for Ontario 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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