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Cheap flights from Ontario to St. Louis from $138

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 3/4. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
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0 bags

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Find the cheapest flights from Ontario to St. Louis

Cheap round-trip flights

Enter your travel dates to find the best prices.
Multiple Airlines Logo
7:10 am - 10:27 pm
YYZ
-
STL
16h 17m
1 stop
Multiple Airlines Logo
4:51 pm - 2:20 pm
STL
-
YYZ
20h 29m
1 stop
$236Multiple Airlines
Wed, Mar 4 - Mon, Mar 9
Multiple Airlines Logo
7:10 am - 10:27 pm
YYZ
-
STL
16h 17m
1 stop
Multiple Airlines Logo
11:32 am - 11:20 pm
STL
-
YYZ
34h 48m
2 stops
$257Multiple Airlines
Wed, Mar 4 - Wed, Mar 11
United Airlines Logo
10:44 am - 9:08 pm
YOW
-
STL
11h 24m
1 stop
United Airlines Logo
7:45 am - 5:07 pm
STL
-
YOW
8h 22m
1 stop
$316United Airlines
Thu, Apr 9 - Sat, Apr 11
United Airlines Logo
5:11 pm - 9:58 pm
YOW
-
STL
5h 47m
1 stop
United Airlines Logo
10:00 am - 5:07 pm
STL
-
YOW
6h 07m
1 stop
$319United Airlines
Fri, Mar 27 - Mon, Mar 30
American Airlines Logo
12:30 pm - 10:17 pm
YUL
-
STL
10h 47m
1 stop
American Airlines Logo
2:33 pm - 11:44 am
STL
-
YUL
20h 11m
1 stop
$349American Airlines
Mon, Apr 20 - Sat, Apr 25
American Airlines Logo
12:30 pm - 11:46 pm
YUL
-
STL
12h 16m
1 stop
American Airlines Logo
8:03 pm - 11:44 am
STL
-
YUL
14h 41m
1 stop
$350American Airlines
Mon, Apr 20 - Sat, Apr 25
Air Canada Logo
7:15 am - 3:29 pm
YOW
-
STL
9h 14m
1 stop
Air Canada Logo
4:05 pm - 11:18 pm
STL
-
YOW
6h 13m
1 stop
$367Air Canada
Sun, Mar 1 - Wed, Mar 4
Air Canada Logo
7:15 am - 3:29 pm
YOW
-
STL
9h 14m
1 stop
Air Canada Logo
4:05 pm - 1:38 am
STL
-
YOW
8h 33m
1 stop
$405Air Canada
Sun, Mar 1 - Wed, Mar 4
Delta Logo
6:45 pm - 11:59 pm
YUL
-
STL
6h 14m
1 stop
Delta Logo
6:04 pm - 11:13 pm
STL
-
YUL
4h 09m
1 stop
$472Delta
Sun, May 10 - Sat, May 16
Delta Logo
7:00 am - 2:24 pm
YUL
-
STL
8h 24m
1 stop
Delta Logo
12:28 pm - 11:40 pm
STL
-
YUL
10h 12m
1 stop
$473Delta
Mon, Mar 16 - Mon, Mar 23

Delta flights from Region of Ontario to St. Louis

Our best Delta deals on Region of Ontario to St. Louis flight tickets
Delta
Feb 24
YYZ5:15 pmToronto Pearson Intl
4h 28m
1 stop
STL8:43 pmLambert-St Louis
Feb 28
STL3:40 pmLambert-St Louis
6h 31m
1 stop
YYZ11:11 pmToronto Pearson Intl
$441
Delta
May 10
YUL6:45 pmMontreal Pierre Elliott Trudeau Intl
6h 14m
1 stop
STL11:59 pmLambert-St Louis
May 16
STL6:04 pmLambert-St Louis
4h 09m
1 stop
YUL11:13 pmMontreal Pierre Elliott Trudeau Intl
$472
Delta
Mar 16
YUL7:00 amMontreal Pierre Elliott Trudeau Intl
8h 24m
1 stop
STL2:24 pmLambert-St Louis
Mar 23
STL12:28 pmLambert-St Louis
10h 12m
1 stop
YUL11:40 pmMontreal Pierre Elliott Trudeau Intl
$473

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
Mar 1
YOW7:15 amOttawa
9h 14m
1 stop
STL3:29 pmLambert-St Louis
Mar 4
STL4:05 pmLambert-St Louis
6h 13m
1 stop
YOW11:18 pmOttawa
$367
Air Canada
Mar 1
YOW7:15 amOttawa
9h 14m
1 stop
STL3:29 pmLambert-St Louis
Mar 4
STL4:05 pmLambert-St Louis
8h 33m
1 stop
YOW1:38 amOttawa
$405
Air Canada
Mar 1
YOW7:15 amOttawa
9h 14m
1 stop
STL3:29 pmLambert-St Louis
Mar 4
STL7:41 amLambert-St Louis
9h 00m
2 stops
YOW5:41 pmOttawa
$416

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 February 7, 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

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 3/4

7:10 am-10:27 pm

1 stop16h 17m

Lambert-St Louis

Mon 3/9

4:51 pm-2:20 pm

1 stop20h 29m

$236

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 3/4

7:10 am-10:27 pm

1 stop16h 17m

Lambert-St Louis

Wed 3/11

11:32 am-11:20 pm

2 stops34h 48m

$257

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Thu 4/9

10:44 am-9:08 pm

1 stop11h 24m

Lambert-St Louis

Sat 4/11

7:45 am-5:07 pm

1 stop8h 22m

$316

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Fri 3/27

5:11 pm-9:58 pm

1 stop5h 47m

Lambert-St Louis

Mon 3/30

10:00 am-5:07 pm

1 stop6h 07m

$319

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Mon 4/20

12:30 pm-10:17 pm

1 stop10h 47m

Lambert-St Louis

Sat 4/25

2:33 pm-11:44 am

1 stop20h 11m

$349

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Mon 4/20

12:30 pm-11:46 pm

1 stop12h 16m

Lambert-St Louis

Sat 4/25

8:03 pm-11:44 am

1 stop14h 41m

$350

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Sun 3/1

7:15 am-3:29 pm

1 stop9h 14m

Lambert-St Louis

Wed 3/4

4:05 pm-11:18 pm

1 stop6h 13m

$367

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Sun 3/1

7:15 am-3:29 pm

1 stop9h 14m

Lambert-St Louis

Wed 3/4

4:05 pm-1:38 am

1 stop8h 33m

$405

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Sun 5/10

6:45 pm-11:59 pm

1 stop6h 14m

Lambert-St Louis

Sat 5/16

6:04 pm-11:13 pm

1 stop4h 09m

$472

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Mon 3/16

7:00 am-2:24 pm

1 stop8h 24m

Lambert-St Louis

Mon 3/23

12:28 pm-11:40 pm

1 stop10h 12m

$473

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 January is another great option to travel to St. Louis, with average flight prices from Region of Ontario averaging around $395.

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 Sunday when prices can be found for as low as $394. 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 Wednesday because tickets tend to average around $496. 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 $446 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 $455 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 9% 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

$394

Fastest flight time

2h 06m

Direct flights

Every day

Airports in St. Louis

1 airport
The best flight deal from Region of Ontario to St. Louis found on momondo in the last 72 hours is $394
The fastest flight from Region of Ontario to St. Louis takes 2h 06m
Direct flights go from Region of Ontario to St. Louis every day.
There is 1 airport in St. Louis. From Region of Ontario there are direct flights to 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 $323Free CancellationRating
7.1
10,697 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
Maryland Heights
Florissant
O'Fallon
Collinsville
St. Peters
Fenton
Wentzville
Alton
Farmington
Clayton
Edwardsville
Eureka
Festus
Litchfield
Glencoe
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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