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Cheap flights from Ontario to St. Louis from C$ 249

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 10/6. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — STL
2 Jun — 9 Jun1
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 3 May 2026.

Sat 23/52:40 p.m.
YOW
-
STL
1 stop6h 45m
Air Canada
Sun 24/57:05 a.m.
STL
-
YOW
1 stop5h 00m
Air Canada
Deal found 30/4C$ 439
Tue 2/66:00 a.m.
YOW
-
STL
2 stops16h 16m
United Airlines
Wed 3/66:00 a.m.
STL
-
YOW
1 stop9h 38m
United Airlines
Deal found 29/4C$ 444
Fri 24/76:25 a.m.
YOW
-
STL
1 stop10h 21m
United Airlines
Sat 8/81:13 p.m.
STL
-
YOW
1 stop7h 22m
United Airlines
Deal found 29/4C$ 446
Thu 4/69:50 a.m.
YYZ
-
STL
1 stop15h 07m
Multiple Airlines
Mon 8/65:27 p.m.
STL
-
YYZ
2 stops19h 38m
Multiple Airlines
Deal found 3/5C$ 465
Wed 27/511:39 a.m.
YYZ
-
STL
1 stop9h 51m
American Airlines
Wed 10/67:03 a.m.
STL
-
YYZ
1 stop9h 41m
American Airlines
Deal found 30/4C$ 467
Thu 24/910:00 a.m.
YOW
-
STL
1 stop5h 00m
Air Canada
Sun 27/912:10 p.m.
STL
-
YOW
1 stop7h 40m
Air Canada
Deal found 2/5C$ 499
Wed 24/67:25 a.m.
YYZ
-
STL
1 stop7h 37m
American Airlines
Tue 30/62:32 p.m.
STL
-
YYZ
1 stop7h 57m
American Airlines
Deal found 2/5C$ 506
Thu 4/67:45 a.m.
YYZ
-
STL
1 stop17h 12m
Multiple Airlines
Thu 18/66:31 p.m.
STL
-
YYZ
2 stops42h 34m
Multiple Airlines
Deal found 2/5C$ 510
Wed 12/86:00 a.m.
YOW
-
STL
2 stops10h 38m
United Airlines
Wed 19/85:00 a.m.
STL
-
YOW
2 stops8h 11m
United Airlines
Deal found 30/4C$ 518
Wed 17/64:45 p.m.
YYZ
-
STL
2 stops26h 51m
Multiple Airlines
Wed 24/64:17 p.m.
STL
-
YYZ
1 stop23h 28m
Multiple Airlines
Deal found 3/5C$ 523
Thu 4/69:50 a.m.
YYZ
-
STL
1 stop15h 07m
Multiple Airlines
Sun 7/67:20 p.m.
STL
-
YYZ
2 stops25h 35m
Multiple Airlines
Deal found 29/4C$ 525
Sat 13/63:45 p.m.
YYZ
-
STL
1 stop5h 12m
American Airlines
Tue 16/61:45 p.m.
STL
-
YYZ
1 stop8h 44m
American Airlines
Deal found 2/5C$ 531

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 3 May 2026.

Round-trip from

C$ 435

One-way from

C$ 249

Popular in

March

Cheapest in

June

Average price

C$ 667

Good round-trip deal

C$ 654 or less

Good one-way deal

C$ 322 or less
United Airlines
  • United Airlines
  • 2/6-3/6
  • 2 total stops
  • 16h 24m total
  • Ontario to St. Louis
Search Deals
10/6
  • 10/6
  • 1 total stop
  • 14h 59m total
  • Ontario to St. Louis
Search Deals
Highest demand for flights based on searches. 23% potential increase in price (C$ 282 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 8% potential price decrease (C$ 72 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in May 2026
Search Deals
Price to beat on a round-trip flight from Ontario to Lambert-St Louis.
Search Deals
Price to beat on a one-way 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 3 May 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 2/6

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

1 stop4h 56m

Lambert-St Louis

Wed 3/6

6:00 a.m.-10:05 p.m.

1 stop15h 05m

C$ 444

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Wed 12/8

6:00 a.m.-9:22 p.m.

2 stops16h 22m

Lambert-St Louis

Wed 19/8

6:00 a.m.-1:59 p.m.

1 stop6h 59m

C$ 446

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Fri 24/7

6:25 a.m.-3:46 p.m.

1 stop10h 21m

Lambert-St Louis

Sat 8/8

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

1 stop7h 22m

C$ 446

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Sat 6/6

5:50 p.m.-11:35 p.m.

1 stop6h 45m

Lambert-St Louis

Mon 6/7

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

1 stop14h 35m

C$ 480

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Sat 6/6

6:05 a.m.-3:46 p.m.

2 stops10h 41m

Lambert-St Louis

Sat 20/6

1:13 p.m.-11:54 p.m.

2 stops9h 41m

C$ 480

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Sun 31/5

3:10 p.m.-11:35 p.m.

1 stop9h 25m

Lambert-St Louis

Sun 7/6

6:00 a.m.-10:05 p.m.

1 stop15h 05m

C$ 480
Quickest round-trip

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Mon 25/5

11:00 a.m.-12:06 p.m.

Nonstop2h 06m

Lambert-St Louis

Fri 29/5

7:05 a.m.-9:56 a.m.

Nonstop1h 51m

C$ 561

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sun 17/5

7:00 a.m.-12:47 p.m.

1 stop6h 47m

Lambert-St Louis

Sun 24/5

5:29 p.m.-11:59 p.m.

1 stop5h 30m

C$ 579

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sat 13/6

7:00 a.m.-12:07 p.m.

1 stop6h 07m

Lambert-St Louis

Tue 16/6

9:23 a.m.-3:46 p.m.

1 stop5h 23m

C$ 587

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 3/6

11:00 a.m.-2:23 p.m.

1 stop4h 23m

Lambert-St Louis

Sat 6/6

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

1 stop4h 04m

C$ 588

Flights are sorted by cheapest round-trip flights first.

Deals found on 28/4

Showing 1-10 of 49 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

How far ahead should I book a flight from Region of Ontario to St. Louis?

To ensure you get the cheapest price possible for a flight from Region of Ontario to St. Louis, you should look to book at least 62 days in advance of your intended travel date. The price of your flight may increase if you delay and leave booking until a week or so before departure.

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$ 228). Flying from Region of Ontario to St. Louis in April is currently the most expensive (average of C$ 503). 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 3 May 2026.

It’s optimal to fly from Region of Ontario to St. Louis in the morning. By choosing this option you can save up to 29% on the cost of your flight, compared to a flight in the evening.

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 3 May 2026.

The most flights from CAON to STL are scheduled on a Monday (4 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (2 on average).

How much does it cost to fly round-trip from Region of Ontario to St. Louis?

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?

    United Airlines, Air Canada, and Delta can get you from Region of Ontario to St. Louis in just under 2h 06m. Your travel time can differ by up to 14h 10m. The distance between Region of Ontario and St. Louis is about 1051 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 Air Canada (92%), United Airlines (83%) or Jazz (83%) 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$ 532, our data indicates the cheapest price to be C$ 322. The most popular route (Toronto Pearson Intl - Lambert-St Louis), is priced around C$ 496.

  • 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$ 228). Flying from Region of Ontario to St. Louis in April is currently the most expensive (average of C$ 503). 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 3 May 2026.
AirlineCheapestAverageFlexibilityOn-time
United AirlinesCheapestC$ 332AverageC$ 638FlexibilityNo cancel feeOn-time69%
Search United Airlines flights
American AirlinesCheapestC$ 359AverageC$ 674FlexibilityNo cancel feeOn-time71%
Search American Airlines flights
Air CanadaCheapestC$ 400AverageC$ 753FlexibilityNo cancel feeOn-time67%
Search Air Canada flights
DeltaCheapestC$ 467AverageC$ 603FlexibilityNo cancel feeOn-timeN/A
Search Delta flights
WestJetCheapestC$ 548AverageC$ 970FlexibilityNo 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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