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Cheap flights from Ontario to St. Louis from C$ 210

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 29/10. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — STL
15 Oct — 22 Oct1
1 adult
1 adult, Economy

Cheap 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 15 September 2025.

Round-trip from

C$ 396

One-way from

C$ 210

Popular in

January

Cheapest in

June

Average price

C$ 695

Good round-trip deal

C$ 540 or less

Good one-way deal

C$ 875 or less
30/10-6/11
  • 30/10-6/11
  • 3 total stops
  • 72h 30m total
  • Ontario to St. Louis
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29/10
  • 29/10
  • 2 total stops
  • 26h 27m total
  • Ontario to St. Louis
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Highest demand for flights based on searches. 7% potential increase in price (C$ 74 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 Ontario to Lambert-St Louis.
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Price to beat on a one-way flight from Ontario to Lambert-St Louis.
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Find flight deals from Ontario to St. Louis

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 15 September 2025.

Fri 17/108:05 p.m.YYZ - STL
1 stop20h 51mMultiple Airlines
Mon 20/109:59 p.m.STL - YYZ
2 stops23h 53mMultiple Airlines
Deal found 12/9C$ 363
Thu 6/119:45 a.m.YYZ - STL
1 stop29h 12mMultiple Airlines
Mon 10/119:07 p.m.STL - YYZ
1 stop21h 48mMultiple Airlines
Deal found 13/9C$ 392
Thu 30/109:45 a.m.YYZ - STL
1 stop29h 12mMultiple Airlines
Thu 6/116:22 p.m.STL - YYZ
2 stops43h 18mMultiple Airlines
Deal found 14/9C$ 396
Mon 20/1010:40 a.m.YYZ - STL
2 stops23h 27mMultiple Airlines
Thu 23/1010:57 a.m.STL - YYZ
1 stop26h 08mMultiple Airlines
Deal found 15/9C$ 410
Mon 29/94:00 p.m.YYZ - STL
2 stops27h 36mMultiple Airlines
Thu 2/1010:35 a.m.STL - YYZ
1 stop9h 20mMultiple Airlines
Deal found 15/9C$ 448
Mon 6/109:50 a.m.YYZ - STL
1 stop11h 47mMultiple Airlines
Mon 13/109:59 p.m.STL - YYZ
2 stops38h 39mMultiple Airlines
Deal found 13/9C$ 461
Fri 5/1212:50 p.m.YYZ - STL
1 stop10h 56mMultiple Airlines
Sun 7/129:50 p.m.STL - YYZ
2 stops20h 46mMultiple Airlines
Deal found 14/9C$ 463
Sat 4/106:30 a.m.YYZ - STL
1 stop28h 32mMultiple Airlines
Mon 6/109:32 p.m.STL - YYZ
1 stop15h 20mMultiple Airlines
Deal found 15/9C$ 466
Sun 12/1010:25 p.m.YYZ - STL
2 stops35h 42mMultiple Airlines
Sun 19/1010:57 a.m.STL - YYZ
1 stop26h 08mMultiple Airlines
Deal found 14/9C$ 475
Wed 29/107:50 a.m.YUL - STL
2 stops11h 30mAmerican Airlines
Wed 5/115:40 p.m.STL - YUL
1 stop20h 31mAmerican Airlines
Deal found 14/9C$ 501
Tue 28/1012:30 p.m.YUL - STL
1 stop8h 56mAmerican Airlines
Tue 4/116:00 a.m.STL - YUL
2 stops15h 39mAmerican Airlines
Deal found 13/9C$ 506
Sat 11/103:50 p.m.YOW - STL
1 stop19h 12mMultiple Airlines
Sat 18/107:15 p.m.STL - YOW
2 stops20h 42mMultiple Airlines
Deal found 14/9C$ 521

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 15 September 2025.
Use the filters below to find and compare flights from Ontario to St. Louis that are best for you.

Fly from

Ontario

Fly to

St. Louis

Route

Depart

Return

Price

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Thu 30/10

9:45 a.m.-1:57 p.m.

1 stop29h 12m

Lambert-St Louis

Thu 6/11

6:22 p.m.-2:40 p.m.

2 stops43h 18m

C$ 396

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Fri 17/10

8:05 p.m.-3:56 p.m.

1 stop20h 51m

Lambert-St Louis

Mon 20/10

6:05 p.m.-10:40 p.m.

1 stop27h 35m

C$ 408

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Thu 6/11

9:45 a.m.-9:07 a.m.

2 stops24h 22m

Lambert-St Louis

Mon 10/11

2:12 p.m.-12:11 a.m.

1 stop8h 59m

C$ 435

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Mon 6/10

9:50 a.m.-8:37 p.m.

1 stop11h 47m

Lambert-St Louis

Mon 13/10

9:59 p.m.-1:38 p.m.

2 stops38h 39m

C$ 461

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Thu 13/11

7:55 p.m.-1:57 p.m.

1 stop19h 02m

Lambert-St Louis

Sun 16/11

7:45 p.m.-11:46 a.m.

2 stops15h 01m

C$ 503

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Tue 28/10

12:30 p.m.-8:26 p.m.

1 stop8h 56m

Lambert-St Louis

Tue 4/11

6:00 a.m.-10:39 p.m.

2 stops15h 39m

C$ 506

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Wed 29/10

7:50 a.m.-6:20 p.m.

2 stops11h 30m

Lambert-St Louis

Wed 5/11

6:00 a.m.-10:39 p.m.

2 stops15h 39m

C$ 508

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Sat 11/10

3:50 p.m.-10:02 a.m.

1 stop19h 12m

Lambert-St Louis

Sat 18/10

7:15 p.m.-4:57 p.m.

2 stops20h 42m

C$ 521

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Fri 5/12

10:58 a.m.-9:47 p.m.

1 stop11h 49m

Lambert-St Louis

Sun 7/12

6:00 a.m.-10:56 a.m.

1 stop3h 56m

C$ 546

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sat 25/10

3:10 p.m.-10:06 p.m.

1 stop7h 56m

Lambert-St Louis

Sun 2/11

5:00 a.m.-11:32 a.m.

1 stop5h 32m

C$ 551

Flights are sorted by cheapest round-trip flights first.

Deals found on 14/9

Showing 1-10 of 43 results
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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, January is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of C$ 365). Flying from Region of Ontario 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 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 15 September 2025.

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 15 September 2025.

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

    American Airlines and United Airlines can get you from Region of Ontario to St. Louis in just under 8h 56m. Your travel time can differ by up to 16h 53m. The distance between Region of Ontario and St. Louis is about 1556 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 (75%), Jazz (75%) or United Airlines (75%) 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$ 1,162, our data indicates the cheapest price to be C$ 435. The most popular route (Toronto Pearson Intl - Lambert-St Louis), is priced around C$ 392.

  • 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, January is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of C$ 365). Flying from Region of Ontario 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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Alternative routes for Ontario to St. Louis

See prices for flight routes from nearby airports that may be better suited for you.
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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 15 September 2025.
AirlineCheapestAverageFlexibilityOn-time
United AirlinesCheapestC$ 321AverageC$ 817FlexibilityNo cancel feeOn-time69%
Search United Airlines flights
American AirlinesCheapestC$ 430AverageC$ 685FlexibilityNo cancel feeOn-time71%
Search American Airlines flights
Air CanadaCheapestC$ 471AverageC$ 774FlexibilityNo cancel feeOn-time67%
Search Air Canada flights
DeltaCheapestC$ 475AverageC$ 654FlexibilityNo cancel feeOn-timeN/A
Search Delta flights
WestJetCheapestC$ 557AverageC$ 869FlexibilityNo 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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