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Cheap flights from St. Louis to Ontario from $134

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from St. Louis to Ontario departing on 11/2. 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 St. Louis to Ontario

Cheap round-trip flights

American Airlines Logo
6:00 am - 3:11 pmSTL-YUL
8h 11m1 stop
American Airlines Logo
3:52 pm - 8:10 amYUL-STL
17h 18m1 stop
$333American Airlines
Find Deal
jue., nov. 6 - dom., nov. 9
American Airlines Logo
7:16 am - 5:40 pmSTL-YYZ
9h 24m1 stop
American Airlines Logo
3:10 pm - 11:54 pmYYZ-STL
9h 44m1 stop
$345American Airlines
Find Deal
lun., oct. 13 - mié., oct. 15
Logo
9:50 am - 9:07 pmSTL-YYZ
10h 17m2 stops
Logo
9:35 am - 5:45 pmYYZ-STL
9h 10m1 stop
$349
Find Deal
sáb., oct. 11 - sáb., oct. 18
Logo
10:35 am - 8:55 pmSTL-YYZ
9h 20m1 stop
Logo
8:00 pm - 1:02 pmYYZ-STL
18h 02m1 stop
$364
Find Deal
jue., sep. 25 - dom., sep. 28
United Airlines Logo
6:43 pm - 1:25 pmSTL-YYZ
17h 42m2 stops
United Airlines Logo
4:30 pm - 3:46 pmYYZ-STL
24h 16m1 stop
$407United Airlines
Find Deal
sáb., nov. 8 - dom., nov. 9
United Airlines Logo
5:27 pm - 9:58 amSTL-YYZ
15h 31m1 stop
United Airlines Logo
6:30 pm - 2:23 pmYYZ-STL
20h 53m1 stop
$471United Airlines
Find Deal
sáb., dic. 6 - dom., dic. 7
Delta Logo
12:29 pm - 9:48 pmSTL-YUL
8h 19m1 stop
Delta Logo
5:00 pm - 11:22 amYUL-STL
19h 22m1 stop
$475Delta
Find Deal
mar., sep. 9 - vie., sep. 19
Delta Logo
6:05 am - 9:57 pmSTL-YUL
14h 52m1 stop
Delta Logo
5:00 pm - 11:22 amYUL-STL
19h 22m1 stop
$489Delta
Find Deal
lun., sep. 15 - vie., sep. 19
Air Canada Logo
4:05 pm - 7:00 pmSTL-YYZ
1h 55mnonstop
Air Canada Logo
6:35 pm - 7:38 pmYYZ-STL
2h 03mnonstop
$555Air Canada
Find Deal
mié., sep. 10 - vie., sep. 12
Air Canada Logo
4:05 pm - 7:00 pmSTL-YYZ
1h 55mnonstop
Air Canada Logo
1:00 pm - 7:57 pmYYZ-STL
7h 57m1 stop
$560Air Canada
Find Deal
lun., sep. 15 - jue., sep. 18

American Airlines flights from St. Louis to Region of Ontario

Our best American Airlines deals on St. Louis to Region of Ontario flight tickets
American Airlines
Nov 6
STL6:00 amLambert-St Louis
8h 11m
1 stop
YUL3:11 pmMontreal Pierre Elliott Trudeau Intl
Nov 9
YUL3:52 pmMontreal Pierre Elliott Trudeau Intl
17h 18m
1 stop
STL8:10 amLambert-St Louis
$333
Find similar
American Airlines
Oct 13
STL7:16 amLambert-St Louis
9h 24m
1 stop
YYZ5:40 pmToronto Pearson Intl
Oct 15
YYZ3:10 pmToronto Pearson Intl
9h 44m
1 stop
STL11:54 pmLambert-St Louis
$345
Find similar
American Airlines
Oct 16
STL7:16 amLambert-St Louis
8h 23m
1 stop
YUL4:39 pmMontreal Pierre Elliott Trudeau Intl
Oct 25
YUL12:30 pmMontreal Pierre Elliott Trudeau Intl
10h 36m
1 stop
STL10:06 pmLambert-St Louis
$348
Find similar

United Airlines flights from St. Louis to Region of Ontario

Our best United Airlines deals on St. Louis to Region of Ontario flight tickets
United Airlines
Nov 8
STL6:43 pmLambert-St Louis
17h 42m
2 stops
YYZ1:25 pmToronto Pearson Intl
Nov 9
YYZ4:30 pmToronto Pearson Intl
24h 16m
1 stop
STL3:46 pmLambert-St Louis
$407
Find similar
United Airlines
Dec 6
STL5:27 pmLambert-St Louis
15h 31m
1 stop
YYZ9:58 amToronto Pearson Intl
Dec 7
YYZ6:30 pmToronto Pearson Intl
20h 53m
1 stop
STL2:23 pmLambert-St Louis
$471
Find similar
United Airlines
Sep 10
STL6:00 amLambert-St Louis
12h 05m
2 stops
YYZ7:05 pmToronto Pearson Intl
Sep 12
YYZ2:10 pmToronto Pearson Intl
26h 34m
1 stop
STL3:44 pmLambert-St Louis
$557
Find similar

momondo Fare Finder

 
Customize your flight search to find flights from St. Louis to Region of Ontario 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 agosto 14, 2025.
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

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

jue. 11/6

6:00 am-3:11 pm

1 stop8h 11m

Montreal Pierre Elliott Trudeau Intl

dom. 11/9

3:52 pm-8:10 am

1 stop17h 18m

$333

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

lun. 10/13

7:16 am-5:40 pm

1 stop9h 24m

Toronto Pearson Intl

mié. 10/15

3:10 pm-11:54 pm

1 stop9h 44m

$345

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

sáb. 10/11

9:50 am-9:07 pm

2 stops10h 17m

Toronto Pearson Intl

sáb. 10/18

9:35 am-5:45 pm

1 stop9h 10m

$349

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

jue. 9/25

10:35 am-8:55 pm

1 stop9h 20m

Toronto Pearson Intl

dom. 9/28

8:00 pm-1:02 pm

1 stop18h 02m

$364

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

sáb. 11/8

6:43 pm-1:25 pm

2 stops17h 42m

Toronto Pearson Intl

dom. 11/9

4:30 pm-3:46 pm

1 stop24h 16m

$407

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

sáb. 12/6

5:27 pm-9:58 am

1 stop15h 31m

Toronto Pearson Intl

dom. 12/7

6:30 pm-2:23 pm

1 stop20h 53m

$471

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

mar. 9/9

12:29 pm-9:48 pm

1 stop8h 19m

Montreal Pierre Elliott Trudeau Intl

vie. 9/19

5:00 pm-11:22 am

1 stop19h 22m

$475

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

lun. 9/15

6:05 am-9:57 pm

1 stop14h 52m

Montreal Pierre Elliott Trudeau Intl

vie. 9/19

5:00 pm-11:22 am

1 stop19h 22m

$489

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

mié. 9/10

4:05 pm-7:00 pm

Nonstop1h 55m

Toronto Pearson Intl

vie. 9/12

6:35 pm-7:38 pm

Nonstop2h 03m

$555

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

lun. 9/15

4:05 pm-7:00 pm

Nonstop1h 55m

Toronto Pearson Intl

jue. 9/18

1:00 pm-7:57 pm

1 stop7h 57m

$560

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 Ontario from

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

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 Region of Ontario?

The month of November is, on average, the cheapest month to fly to Region of Ontario from St. Louis, with most prices found around $267. If you aren’t able to travel during the month of November, then book flights to Region of Ontario from St. Louis during January instead. Flights to Region of Ontario in January, while not as cheap as those in November, still average around $286.

What is the cheapest day to depart on your flight to Region of Ontario?

According to our data, Thursday is the cheapest day to fly to Region of Ontario from St. Louis. The lowest ticket price found for a Thursday departure recently was $865. Keep in mind that prices can always vary depending on your route and whether or not you are flying domestic or international. Flights from St. Louis to Region of Ontario on a Friday will generally be more expensive and average around $1,004. Keep in mind that these prices on both days could fluctuate depending on the season and the demand.

What is the cheapest time of day to depart on your flight to Region of Ontario?

According to our data, the cheapest time of day to fly to Region of Ontario is in the afternoon. momondo users have found flights departing from St. Louis to Region of Ontario in the afternoon for as low as $913. Keep in mind that these prices may fluctuate based on what airline you choose and the time of year you plan to travel. Flights at noon are often more expensive with an average ticket price of $1,180.

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

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

How far in advance should I book a flight to Region of Ontario?

You are more likely to see cheaper flights to Region of Ontario from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to Region of Ontario for around $457 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Region of Ontario from St. Louis for as low as $221 on momondo.

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

There are 4 cabin classes available to choose from on Lambert-St Louis to Ontario 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 St. Louis to Region of Ontario flights?

You could potentially save up to 10% on your flight if you consider stops on a St. Louis to Region of Ontario flight.

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

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

Best Price Found

$134

Fastest flight time

1h 55m

Direct flights

Every day

Airports in Region of Ontario

3 airports
The best one-way flight to Region of Ontario from St. Louis in the past 72 hours is $134. The best round-trip flight deal from St. Louis to Region of Ontario found on momondo in the last 72 hours is $333.
The fastest flight from St. Louis to Region of Ontario takes 1h 55m
Direct flights go from St. Louis to Region of Ontario every day.
There are 3 airports near Region of Ontario: Ottawa (YOW), Montreal Pierre Elliott Trudeau Intl (YUL), Toronto Pearson Intl (YYZ)
Search flight deals

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

    Prices for flights from Lambert-St Louis Airport to Ontario were last updated today.

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

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

    The minimum age for a child to fly alone is five, but airlines offering an unaccompanied minor (UNMR) service may have their age restrictions, such as regulations concerning flight duration, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Lambert-St Louis Airport to Ontario.

  • What documentation or ID do you need to fly to Ontario?

    The required travel and health documents for your Ontario trip may vary depending on your itinerary and personal circumstances. As a general rule, you should carry multiple documents, including a national ID card or driver's license and a passport valid for six months after your intended arrival at Ontario. We recommend that you seek guidance from your airline or a reliable third party such as IATA.

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

Best airlines flying from St. Louis to Region of Ontario

Compare and see reviews for airlines that fly from St. Louis to Region of Ontario with momondo
Airline
Rating
Free Cancellation
Price
United AirlinesPriceFrom $214Free CancellationRating
7.4
8,916 reviews
Search United Airlines flights
Air CanadaPriceFrom $220Free CancellationRating
7.1
9,949 reviews
Search Air Canada flights
American AirlinesPriceFrom $330Free CancellationRating
7.2
10,000 reviews
Search American Airlines flights

Why use momondo?

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

It is quick and easy to find St. Louis to Ontario flights on momondo. We search and return numerous flight options from various airlines and agents. You can then use our filters to narrow your search until you have found the most convenient flight to Ontario that suits you.

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

Yes. All flights to Ontario from St. Louis on momondo can be compared and filtered by various policies on offer, including flexible booking.

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

Once you have performed a search for St. Louis to Ontario flights, momondo helps you find the right one by offering useful filters to narrow down your flight selection. Flights can be filtered by multiple factors such as airline, airport and price; but also by other criteria like aircraft type and payment method.

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

If you are simply researching potential flights to Ontario, momondo offers a useful price alert feature which will track prices for flights to Ontario from St. Louis and alert you when they change.

An easier way to manage your Region of Ontario trip

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Find better results for your trip to Ontario

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