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Cheap flights from St. Louis to Ontario from C$ 190

STL — YYZ
26 Oct — 2 Nov1
1 adult
1 adult, Economy, 0 bags

Cheap flight deals from St. Louis to Ontario

Enter your travel dates to find the best prices.

Cheapest flights from St. Louis to Ontario

Thu 15/105:00 a.m. -
1 stop8h 33m
Mon 19/103:14 p.m. -
1 stop10h 05m
Deal found 22/9C$ 501
Thu 26/115:59 p.m. -
1 stop18h 41m
Tue 1/1212:20 p.m. -
2 stops23h 57m
Deal found 25/9C$ 506
Wed 28/106:44 p.m. -
2 stops19h 36m
Sat 31/106:30 a.m. -
1 stop17h 46m
Deal found 21/9C$ 508
Wed 28/106:44 p.m. -
2 stops19h 36m
Sun 1/114:20 p.m. -
2 stops26h 20m
Deal found 23/9C$ 511
Wed 11/116:44 p.m. -
2 stops19h 36m
Sat 14/116:30 a.m. -
1 stop17h 46m
Deal found 25/9C$ 512
Wed 28/106:44 p.m. -
2 stops19h 36m
Mon 2/116:30 a.m. -
1 stop17h 46m
Deal found 21/9C$ 518
Wed 2/126:13 p.m. -
1 stop18h 27m
Wed 9/1210:40 a.m. -
2 stops49h 37m
Deal found 23/9C$ 522
Sat 24/104:30 p.m. -
1 stop20h 10m
Sun 1/117:35 a.m. -
2 stops35h 05m
Deal found 21/9C$ 530
Fri 30/107:29 a.m. -
1 stop9h 15m
Mon 2/1111:36 a.m. -
1 stop8h 46m
Deal found 21/9C$ 539
Wed 28/106:44 p.m. -
2 stops19h 36m
Wed 4/117:15 a.m. -
2 stops11h 25m
Deal found 24/9C$ 540
Wed 21/106:35 p.m. -
2 stops25h 20m
Sat 31/106:30 a.m. -
1 stop17h 46m
Deal found 23/9C$ 545
Sat 24/104:30 p.m. -
1 stop20h 10m
Tue 27/106:20 p.m. -
2 stops24h 20m
Deal found 21/9C$ 546

Find flight deals from St. Louis to Ontario

Round-trip from

C$ 501

One-way from

C$ 190

Popular in

August

Cheapest in

March

Average price

C$ 979
American Airlines
  • American Airlines
  • 22/10-27/10
  • 2 total stops
  • 19h 39m total
  • St. Louis to Ontario
Search Deals
16/10-31/12
  • 16/10-31/12
  • 2 total stops
  • 25h 59m total
  • St. Louis to Ontario
Search Deals
Highest demand for flights based on searches. 10% potential increase in price (C$ 146 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 1% potential price decrease (C$ 25 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in September 2026
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Cheapflights Fare Finder

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

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Wed 14/10

6:35 p.m.-2:55 p.m.

2 stops43h 20m

Toronto Pearson Intl

Wed 31/12

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

Nonstop0h 00m

C$ 197

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Sat 17/10

11:31 a.m.-11:29 p.m.

1 stop10h 58m

Toronto Pearson Intl

Wed 31/12

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

Nonstop0h 00m

C$ 209

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Thu 22/10

7:03 a.m.-4:47 p.m.

1 stop8h 44m

Toronto Pearson Intl

Wed 31/12

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

Nonstop0h 00m

C$ 297

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Thu 5/11

12:14 p.m.-1:40 p.m.

2 stops24h 26m

Toronto Pearson Intl

Wed 31/12

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

Nonstop0h 00m

C$ 298

St. LouisOttawa

STL Lambert-St Louis - YOW Ottawa

STLYOW

Lambert-St Louis

Mon 9/11

6:44 p.m.-12:44 a.m.

3 stops29h 00m

Ottawa

Wed 31/12

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

Nonstop0h 00m

C$ 308

St. LouisOttawa

STL Lambert-St Louis - YOW Ottawa

STLYOW

Lambert-St Louis

Wed 23/12

2:59 p.m.-3:25 p.m.

2 stops23h 26m

Ottawa

Wed 31/12

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

Nonstop0h 00m

C$ 447

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Thu 22/10

4:30 p.m.-6:28 p.m.

3 stops24h 58m

Toronto Pearson Intl

Wed 31/12

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

Nonstop0h 00m

C$ 470

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Tue 29/12

7:18 a.m.-8:28 p.m.

2 stops12h 10m

Toronto Pearson Intl

Wed 31/12

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

Nonstop0h 00m

C$ 496

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Sat 10/10

4:30 p.m.-1:45 p.m.

1 stop20h 15m

Toronto Pearson Intl

Wed 31/12

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

Nonstop0h 00m

C$ 508

St. LouisOttawa

STL Lambert-St Louis - YOW Ottawa

STLYOW

Lambert-St Louis

Sun 8/11

5:00 a.m.-9:16 p.m.

1 stop15h 16m

Ottawa

Wed 31/12

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

Nonstop0h 00m

C$ 523

Flights are sorted by cheapest round-trip flights first.

Deals found on 24/9

Showing 1-10 of 34 resultsSorted by cheapest first
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Best time to book a flight from St. Louis to Ontario

Have a flexible travel schedule? Discover the best time to fly to Ontario from St. Louis with our price prediction graph.
Estimated round-trip price

Cheapflights Insights

Everything you need to know about your flight from St. Louis to Ontario

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

Currently, March is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of C$ 601). Flying from St. Louis to Region of Ontario in January is currently the most expensive (average of C$ 1,188). 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 STL to ON?

When flying from St. Louis to Region of Ontario, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.

Weekly flight availability from St. Louis to Region of Ontario

The most flights from STL to CAON 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).

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

Airfare is below average for this route at the moment.
St. Louis to Region of Ontario flights typically cost between C$ 812 and C$ 1,020 in October.
The cheapest round-trip price found within the last 5 days was C$ 501 on American Airlines (15 Oct-19 Oct).

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

To ensure you get the cheapest price possible for a flight from St. Louis to Region of Ontario, you should look to book at least 87 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.

Reviews of airlines servicing Ontario

See what other customers who have flown with Air Canada from St. Louis to Ontario have to say. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Air Canada
7.1
Good
11,686 reviews
Check prices

Boarding

7.3

Entertainment

6.8

Crew

7.8

Comfort

7.1

Food

6.3

Overall

7.1

Reviews

1 / 20
2.0
Mediocre

Shawna,Sep 2025

DCA - YYZ

Business class cabin was *freezing*. Landing was so hard it injured my back - no apology or explanation given
Air Canada
7.1
Good
11,686 reviews
Air Canada
7.1
Good
11,686 reviews
Check prices

Boarding

7.3

Entertainment

6.8

Crew

7.8

Comfort

7.1

Food

6.3

Overall

7.1

Reviews

1 / 20
2.0
Mediocre

Shawna,Sep 2025

DCA - YYZ

Business class cabin was *freezing*. Landing was so hard it injured my back - no apology or explanation given

Related info for your journey

  • What airport do you fly from for flights from St. Louis to Ontario?

    If you book a flight to Ontario from St. Louis, you will be flying from Lambert-St Louis, which is the city’s only airport. Lambert-St Louis (STL) is located 20.4 km from the centre of St. Louis.

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

    Departing from St. Louis to Region of Ontario will take you 8h 44m. St. Louis and Region of Ontario are separated by a distance of 1051 km. Both multi-stop and direct flights can be found to your destination and back.

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

    The most popular flight routes from St. Louis to Region of Ontario are Lambert-St Louis - Toronto Pearson Intl, Lambert-St Louis - Montreal Pierre Elliott Trudeau Intl and Lambert-St Louis - London.

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

    Before booking your flight to Region of Ontario from St. Louis, check out the most reliable airlines to get you to your destination on time: Air Canada (70%), Jazz (70%), United Airlines( 68%).

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

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

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

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

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

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

    Currently, March is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of C$ 601). Flying from St. Louis to Region of Ontario in January is currently the most expensive (average of C$ 1,188). 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

Browse thousands of different options on Cheapflights for your next trip

Top airline flying from St. Louis to Ontario

AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapestC$ 335AverageC$ 659FlexibilityNo cancel feeOn-time67%
Search Air Canada flights

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Cheapflights helps you search for flights from St. Louis to Ontario via 900+ travel sites so you don’t have to. After performing a flight search, users can also filter their flight selection by filtering for price, number of stops, airlines, and so on.

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

By finding flights from multiple airlines and providers at completely no cost, Cheapflights helps millions of users like you annually find the best flights to Ontario from St. Louis.

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

Certainly. Search results for flights to Ontario from St. Louis 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 St. Louis to Ontario become cheaper?

Yes! Start tracking prices for St. Louis to Ontario 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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