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Cheap flights from Ontario to St. Louis from $169

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from Ontario to St. Louis departing on 10/6. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
1 adult
0 bags

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Find the cheapest flights from Ontario to St. Louis

Cheap round-trip flights

Multiple Airlines Logo
1:35 pm - 10:02 amYYZ-STL
21h 27m1 stop
Multiple Airlines Logo
10:57 am - 2:05 pmSTL-YYZ
26h 08m1 stop
$266Multiple Airlines
Find Deal
Sat, Oct 18 - Thu, Oct 23
Multiple Airlines Logo
1:35 pm - 10:02 amYYZ-STL
21h 27m1 stop
Multiple Airlines Logo
11:32 am - 2:05 pmSTL-YYZ
25h 33m2 stops
$292Multiple Airlines
Find Deal
Sat, Oct 18 - Thu, Oct 23
American Airlines Logo
12:30 pm - 10:08 pmYUL-STL
10h 38m1 stop
American Airlines Logo
7:58 pm - 3:11 pmSTL-YUL
18h 13m1 stop
$363American Airlines
Find Deal
Sat, Nov 1 - Sat, Nov 8
American Airlines Logo
7:50 am - 6:11 pmYUL-STL
11h 21m2 stops
American Airlines Logo
4:42 pm - 3:11 pmSTL-YUL
21h 29m1 stop
$372American Airlines
Find Deal
Sat, Nov 1 - Sat, Nov 8
Air Canada Logo
2:15 pm - 3:18 pmYYZ-STL
2h 03mnonstop
Air Canada Logo
4:05 pm - 7:06 pmSTL-YYZ
2h 01mnonstop
$383Air Canada
Find Deal
Sat, Oct 25 - Sun, Nov 2
Air Canada Logo
2:00 pm - 3:29 pmYYZ-STL
2h 29mnonstop
Air Canada Logo
4:05 pm - 7:06 pmSTL-YYZ
2h 01mnonstop
$385Air Canada
Find Deal
Sat, Nov 1 - Wed, Nov 5
United Airlines Logo
11:00 am - 2:27 pmYYZ-STL
4h 27m1 stop
United Airlines Logo
5:28 pm - 11:58 pmSTL-YYZ
5h 30m1 stop
$427United Airlines
Find Deal
Sat, Oct 25 - Sat, Oct 25
Delta Logo
6:45 pm - 11:38 amYYZ-STL
17h 53m1 stop
Delta Logo
3:59 pm - 9:55 pmSTL-YYZ
4h 56m1 stop
$432Delta
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Fri, Oct 31 - Sun, Nov 2
United Airlines Logo
3:00 pm - 10:35 pmYYZ-STL
8h 35m2 stops
United Airlines Logo
6:30 am - 2:19 pmSTL-YYZ
6h 49m2 stops
$435United Airlines
Find Deal
Wed, Oct 1 - Fri, Oct 3
Delta Logo
7:30 pm - 8:13 amYUL-STL
13h 43m1 stop
Delta Logo
9:35 am - 6:40 pmSTL-YUL
8h 05m1 stop
$466Delta
Find Deal
Wed, Nov 5 - Wed, Nov 12

Air Canada flights from Region of Ontario to St. Louis

Our best Air Canada deals on Region of Ontario to St. Louis flight tickets
Air Canada
Oct 25
YYZ2:15 pmToronto Pearson Intl
2h 03m
STL3:18 pmLambert-St Louis
Nov 2
STL4:05 pmLambert-St Louis
2h 01m
YYZ7:06 pmToronto Pearson Intl
$383
Find similar
Air Canada
Nov 1
YYZ2:00 pmToronto Pearson Intl
2h 29m
STL3:29 pmLambert-St Louis
Nov 5
STL4:05 pmLambert-St Louis
2h 01m
YYZ7:06 pmToronto Pearson Intl
$385
Find similar
Air Canada
Oct 15
YYZ2:15 pmToronto Pearson Intl
2h 03m
STL3:18 pmLambert-St Louis
Oct 22
STL4:05 pmLambert-St Louis
1h 55m
YYZ7:00 pmToronto Pearson Intl
$401
Find similar

American Airlines flights from Region of Ontario to St. Louis

Our best American Airlines deals on Region of Ontario to St. Louis flight tickets
American Airlines
Nov 1
YUL12:30 pmMontreal Pierre Elliott Trudeau Intl
10h 38m
1 stop
STL10:08 pmLambert-St Louis
Nov 8
STL7:58 pmLambert-St Louis
18h 13m
1 stop
YUL3:11 pmMontreal Pierre Elliott Trudeau Intl
$363
Find similar
American Airlines
Nov 1
YUL7:50 amMontreal Pierre Elliott Trudeau Intl
11h 21m
2 stops
STL6:11 pmLambert-St Louis
Nov 8
STL4:42 pmLambert-St Louis
21h 29m
1 stop
YUL3:11 pmMontreal Pierre Elliott Trudeau Intl
$372
Find similar
American Airlines
Oct 15
YYZ1:15 pmToronto Pearson Intl
11h 39m
1 stop
STL11:54 pmLambert-St Louis
Oct 21
STL6:00 amLambert-St Louis
7h 30m
1 stop
YYZ2:30 pmToronto Pearson Intl
$377
Find similar

momondo Fare Finder

 
Customize your flight search to find flights from Region of 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, momondo users made 832,500 searches. Data last updated September 19, 2025.
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

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sat 10/18

1:35 pm-10:02 am

1 stop21h 27m

Lambert-St Louis

Thu 10/23

10:57 am-2:05 pm

1 stop26h 08m

$266

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sat 10/18

1:35 pm-10:02 am

1 stop21h 27m

Lambert-St Louis

Thu 10/23

11:32 am-2:05 pm

2 stops25h 33m

$292

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Sat 11/1

12:30 pm-10:08 pm

1 stop10h 38m

Lambert-St Louis

Sat 11/8

7:58 pm-3:11 pm

1 stop18h 13m

$363

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Sat 11/1

7:50 am-6:11 pm

2 stops11h 21m

Lambert-St Louis

Sat 11/8

4:42 pm-3:11 pm

1 stop21h 29m

$372

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sat 10/25

2:15 pm-3:18 pm

Nonstop2h 03m

Lambert-St Louis

Sun 11/2

4:05 pm-7:06 pm

Nonstop2h 01m

$383

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sat 11/1

2:00 pm-3:29 pm

Nonstop2h 29m

Lambert-St Louis

Wed 11/5

4:05 pm-7:06 pm

Nonstop2h 01m

$385

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sat 10/25

11:00 am-2:27 pm

1 stop4h 27m

Lambert-St Louis

Sat 10/25

5:28 pm-11:58 pm

1 stop5h 30m

$427

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Fri 10/31

6:45 pm-11:38 am

1 stop17h 53m

Lambert-St Louis

Sun 11/2

3:59 pm-9:55 pm

1 stop4h 56m

$432

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 10/1

3:00 pm-10:35 pm

2 stops8h 35m

Lambert-St Louis

Fri 10/3

6:30 am-2:19 pm

2 stops6h 49m

$435

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Wed 11/5

7:30 pm-8:13 am

1 stop13h 43m

Lambert-St Louis

Wed 11/12

9:35 am-6:40 pm

1 stop8h 05m

$466

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first
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See travel insights to St. Louis from

How to get the cheapest flight ticket from Region of Ontario to St. Louis

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

What is the cheapest month to fly to St. Louis?

In general, June is the cheapest month to fly from Region of Ontario to St. Louis. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $372. The month of August is another great option to travel to St. Louis, with average flight prices from Region of Ontario averaging around $397.

What is the cheapest day to depart on your flight to St. Louis?

The cheapest day to depart on your flight to St. Louis is on a Saturday when prices can be found for as low as $405. This is often the case because there is less demand to fly during this day of the week. If your travel schedule is flexible, try to avoid departing on a Sunday because tickets tend to average around $541. These prices are subject to change though, so be sure to set up a Price Alert for flights to St. Louis.

What is the cheapest time of day to depart on your flight to St. Louis?

Flying to St. Louis from Region of Ontario in the morning is the least expensive time of day to depart. momondo users have found prices as low as $326 when looking at flights departing in the morning. At noon is when there is more demand to fly to St. Louis, so prices are often more expensive at around $480 per ticket.

What is the cheapest Ontario to Lambert-St Louis flight route?

Fly from Toronto Pearson Intl to Lambert-St Louis for the best Ontario - Lambert-St Louis flight prices

How far in advance should I book a flight to St. Louis?

You are more likely to see cheaper flights to St. Louis from Region of Ontario when booking weeks ahead of your departure date. In general, you can expect to find flights to St. Louis for around $493 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to St. Louis from Region of Ontario for as low as $360 on momondo.

What cabin class options are available on Ontario to Lambert-St Louis flights?

There are 3 cabin classes available to choose from on Ontario to Lambert-St Louis flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on Region of Ontario to St. Louis flights?

You could potentially save up to 2% on your flight if you consider stops on a Region of Ontario to St. Louis flight.

Cheap Region of Ontario to St. Louis flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Region of Ontario to St. Louis

Best Price Found

$283

Fastest flight time

2h 03m

Direct flights

Every day

Airports in St. Louis

1 airport
The best one-way flight to St. Louis from Region of Ontario in the past 72 hours is $283. The best round-trip flight deal from Region of Ontario to St. Louis found on momondo in the last 72 hours is $405.
The fastest flight from Region of Ontario to St. Louis takes 2h 03m
Direct flights go from Region of Ontario to St. Louis every day.
There is 1 airport near St. Louis: Lambert-St Louis (STL)
Search flight deals

  • When did momondo last update prices for flights from Ontario to Lambert-St Louis Airport?

    Prices for flights from Ontario to Lambert-St Louis Airport refresh daily.

  • How many operators does momondo search for flights from Ontario to Lambert-St Louis Airport?

  • How old do you have to be to fly from Ontario to Lambert-St Louis Airport?

    The minimum age for a child to fly alone is five, but airlines that offer an unaccompanied minor (UNMR) service may have their own age limitations. Flight duration, scheduling, and layovers are among the considerations that may influence age limits. We recommend that you double-check with the airline you are booking with for travel from Ontario to Lambert-St Louis Airport.

  • What documentation or ID do you need to fly to Lambert-St Louis Airport?

    The travel and health documents required for your trip to Lambert-St Louis Airport can vary based on your itinerary and personal situation. As a rule, consider having multiple documents such as a national ID card or driver’s license, and a passport valid for six-months after you plan to arrive at Lambert-St Louis Airport. We always recommend checking with your airline or a trusted third party such as IATA to get advice.

  • What is the most popular plane model from Region of Ontario to St. Louis?

Best airlines flying from Region of Ontario to St. Louis

Compare and see reviews for airlines that fly from Region of Ontario to St. Louis with momondo
Airline
Rating
Free Cancellation
Price
Air CanadaPriceFrom $324Free CancellationRating
7.1
10,000 reviews
Search Air Canada flights

Traveling to a place near St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
St. Charles
Chesterfield
Hermann
Fairview Heights
Florissant
Maryland Heights
O'Fallon
Fenton
Collinsville
Wentzville
Alton
St. Peters
Farmington
Festus
Glencoe
Clayton
Edwardsville
Eureka
Litchfield
Shrewsbury

Why use momondo?

Why should I use momondo to find a flight deal from Ontario to St. Louis?

momondo compares prices from hundreds of airlines and agents so you can find and book the best deal on flights from Ontario to St. Louis. Millions of users trust and use momondo every year so you are in good hands.

Can I find flights from Ontario to St. Louis with flexible booking policies on momondo?

Flights from Ontario to St. Louis with flexible booking policies can be found by using the search form above and then selecting our dedicated flexible booking filter, which will highlight only the flights where this policy is applied.

How can momondo help me find flights from Ontario to St. Louis?

Once all potential Ontario to St. Louis flight options are in front of you, momondo lets you sort and filter flights based on preferences such as airline, price and flight times amongst many other options.

I’m not ready to book a flight from Ontario to St. Louis right now. Can momondo alert me if prices change?

Price alerts on flights to St. Louis from Ontario are quick and easy to set up on momondo. Simply perform a search and select the price alert feature. It is as simple as that.

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