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Cheap flights from Ontario to St. Louis from $191

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 9/19. 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

American Airlines Logo
4:44 pm - 11:56 pmYYZ-STL
8h 12m1 stop
American Airlines Logo
6:00 am - 4:04 pmSTL-YYZ
9h 04m1 stop
$322American Airlines
Find Deal
Sat, Nov 8 - Sat, Nov 15
American Airlines Logo
12:30 pm - 8:32 pmYUL-STL
9h 02m1 stop
American Airlines Logo
9:56 am - 11:46 amSTL-YUL
24h 50m1 stop
$323American Airlines
Find Deal
Wed, Sep 3 - Sat, Sep 6
Logo
6:30 am - 5:55 pmYYZ-STL
12h 25m1 stop
Logo
2:22 pm - 8:00 pmSTL-YYZ
28h 38m1 stop
$343
Find Deal
Sat, Oct 25 - Sun, Oct 26
Logo
6:30 am - 9:40 amYYZ-STL
28h 10m1 stop
Logo
10:35 am - 8:55 pmSTL-YYZ
9h 20m1 stop
$373
Find Deal
Sat, Aug 30 - Thu, Sep 4
Delta Logo
11:00 am - 10:02 pmYUL-STL
12h 02m2 stops
Delta Logo
7:00 am - 8:04 pmSTL-YUL
12h 04m2 stops
$385Delta
Find Deal
Wed, Sep 3 - Sat, Sep 6
United Airlines Logo
2:45 pm - 9:32 pmYYZ-STL
7h 47m1 stop
United Airlines Logo
6:30 am - 9:40 pmSTL-YYZ
14h 10m2 stops
$401United Airlines
Find Deal
Sat, Sep 20 - Sat, Sep 27
Delta Logo
6:00 am - 4:06 pmYUL-STL
11h 06m2 stops
Delta Logo
7:00 am - 8:04 pmSTL-YUL
12h 04m2 stops
$412Delta
Find Deal
Wed, Sep 3 - Sat, Sep 6
United Airlines Logo
8:15 am - 3:44 pmYYZ-STL
8h 29m1 stop
United Airlines Logo
3:20 pm - 11:58 pmSTL-YYZ
7h 38m1 stop
$422United Airlines
Find Deal
Wed, Aug 27 - Wed, Sep 3
Air Canada Logo
2:15 pm - 3:18 pmYYZ-STL
2h 03mnonstop
Air Canada Logo
9:15 am - 12:11 pmSTL-YYZ
1h 56mnonstop
$439Air Canada
Find Deal
Thu, Sep 18 - Thu, Sep 25
Air Canada Logo
2:15 pm - 3:18 pmYYZ-STL
2h 03mnonstop
Air Canada Logo
9:15 am - 12:11 pmSTL-YYZ
1h 56mnonstop
$441Air Canada
Find Deal
Thu, Sep 11 - Mon, Sep 15

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 8
YYZ4:44 pmToronto Pearson Intl
8h 12m
1 stop
STL11:56 pmLambert-St Louis
Nov 15
STL6:00 amLambert-St Louis
9h 04m
1 stop
YYZ4:04 pmToronto Pearson Intl
$322
Find similar
American Airlines
Sep 3
YUL12:30 pmMontreal Pierre Elliott Trudeau Intl
9h 02m
1 stop
STL8:32 pmLambert-St Louis
Sep 6
STL9:56 amLambert-St Louis
24h 50m
1 stop
YUL11:46 amMontreal Pierre Elliott Trudeau Intl
$323
Find similar
American Airlines
Sep 20
YUL12:31 pmMontreal Pierre Elliott Trudeau Intl
9h 01m
1 stop
STL8:32 pmLambert-St Louis
Sep 27
STL5:25 pmLambert-St Louis
17h 21m
1 stop
YUL11:46 amMontreal Pierre Elliott Trudeau Intl
$324
Find similar

Delta flights from Region of Ontario to St. Louis

Our best Delta deals on Region of Ontario to St. Louis flight tickets
Delta
Sep 3
YUL11:00 amMontreal Pierre Elliott Trudeau Intl
12h 02m
2 stops
STL10:02 pmLambert-St Louis
Sep 6
STL7:00 amLambert-St Louis
12h 04m
2 stops
YUL8:04 pmMontreal Pierre Elliott Trudeau Intl
$385
Find similar
Delta
Sep 3
YUL6:00 amMontreal Pierre Elliott Trudeau Intl
11h 06m
2 stops
STL4:06 pmLambert-St Louis
Sep 6
STL7:00 amLambert-St Louis
12h 04m
2 stops
YUL8:04 pmMontreal Pierre Elliott Trudeau Intl
$412
Find similar
Delta
Sep 20
YUL11:00 amMontreal Pierre Elliott Trudeau Intl
11h 50m
2 stops
STL9:50 pmLambert-St Louis
Sep 27
STL7:10 amLambert-St Louis
11h 15m
2 stops
YUL7:25 pmMontreal Pierre Elliott Trudeau Intl
$439
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 August 6, 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 11/8

4:44 pm-11:56 pm

1 stop8h 12m

Lambert-St Louis

Sat 11/15

6:00 am-4:04 pm

1 stop9h 04m

$322

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Wed 9/3

12:30 pm-8:32 pm

1 stop9h 02m

Lambert-St Louis

Sat 9/6

9:56 am-11:46 am

1 stop24h 50m

$323

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sat 10/25

6:30 am-5:55 pm

1 stop12h 25m

Lambert-St Louis

Sun 10/26

2:22 pm-8:00 pm

1 stop28h 38m

$343

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sat 8/30

6:30 am-9:40 am

1 stop28h 10m

Lambert-St Louis

Thu 9/4

10:35 am-8:55 pm

1 stop9h 20m

$373

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Wed 9/3

11:00 am-10:02 pm

2 stops12h 02m

Lambert-St Louis

Sat 9/6

7:00 am-8:04 pm

2 stops12h 04m

$385

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sat 9/20

2:45 pm-9:32 pm

1 stop7h 47m

Lambert-St Louis

Sat 9/27

6:30 am-9:40 pm

2 stops14h 10m

$401

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Wed 9/3

6:00 am-4:06 pm

2 stops11h 06m

Lambert-St Louis

Sat 9/6

7:00 am-8:04 pm

2 stops12h 04m

$412

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 8/27

8:15 am-3:44 pm

1 stop8h 29m

Lambert-St Louis

Wed 9/3

3:20 pm-11:58 pm

1 stop7h 38m

$422

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Thu 9/18

2:15 pm-3:18 pm

Nonstop2h 03m

Lambert-St Louis

Thu 9/25

9:15 am-12:11 pm

Nonstop1h 56m

$439

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Thu 9/11

2:15 pm-3:18 pm

Nonstop2h 03m

Lambert-St Louis

Mon 9/15

9:15 am-12:11 pm

Nonstop1h 56m

$441

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 November is another great option to travel to St. Louis, with average flight prices from Region of Ontario averaging around $464.

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 $392. 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 $488 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 $487 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 11% 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

$191

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 $191. The best round-trip flight deal from Region of Ontario to St. Louis found on momondo in the last 72 hours is $322.
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
9,893 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
Fairview Heights
Hermann
Maryland Heights
Florissant
Fenton
O'Fallon
Collinsville
Alton
Wentzville
St. Peters
Farmington
Festus
Glencoe
Eureka
Edwardsville
Clayton
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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