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$123+ Cheap flights from St. Louis (STL) to Ontario

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 5/9. Fares are subject to change and may not be available on all flights or dates of travel.
STL — YYZ
Apr 22 — Apr 291
Tue 4/22
Tue 4/29
1 adult, Economy
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Cheap flight deals from St. Louis to Ontario

Keep the following information in mind while searching for St. Louis to Ontario flight deals. Data was last updated April 17, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

eDreams
3 stars

Round-trip from

$317
(Kiwi.com)

One-way from

$123
(Kiwi.com)

Popular in

March

Cheapest in

May

Average price

$314

Good round-trip deal

$798 or less

Good one-way deal

$241 or less
Provider with most accurate pricing for Lambert-St Louis-Toronto (YTO) flight deals.
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Provider most trusted by Cheapflights users for Lambert-St Louis-Toronto (YTO) flights.
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From Lambert-St Louis to Ontario
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One-way flight from Lambert-St Louis to Ontario
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Highest demand for flights based on searches. 3% potential increase in price ($13 potential increase over avg. RT price).
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Cheapest flight prices on average. 4% potential price decrease ($17 potential savings vs. average RT price).
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Average for round-trip flights in April 2025
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Price to beat on a round-trip flight from Lambert-St Louis to Ontario.
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Price to beat on a one-way flight from Lambert-St Louis to Ontario.
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Find flight deals from St. Louis to Ontario

Cheapest flights from St. Louis to Ontario
Explore the most affordable flight options available from St. Louis to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on April 17, 2025.

This Kiwi.com deal was found by Cheapflights users on 4/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 6/510:10 amSTL - YYZ
1 stop9h 50mMultiple Airlines
Mon 6/94:00 pmYYZ - STL
1 stop8h 37mMultiple Airlines
Deal found 4/17$317
This Kiwi.com deal was found by Cheapflights users on 4/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/2510:10 amSTL - YOW
1 stop30h 05mMultiple Airlines
Fri 5/303:50 pmYOW - STL
1 stop18h 25mMultiple Airlines
Deal found 4/16$340
This Kiwi.com deal was found by Cheapflights users on 4/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/1510:10 amSTL - YUL
2 stops13h 27mMultiple Airlines
Thu 5/226:45 amYUL - STL
1 stop18h 07mMultiple Airlines
Deal found 4/17$413
This American Airlines deal was found by Cheapflights users on 4/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/86:00 amSTL - YYZ
1 stop7h 30mAmerican Airlines
Mon 5/191:15 pmYYZ - STL
1 stop11h 36mAmerican Airlines
Deal found 4/17$435
This Delta deal was found by Cheapflights users on 4/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 5/55:34 pmSTL - YYZ
1 stop4h 41mDelta
Tue 5/207:55 amYYZ - STL
1 stop13h 53mDelta
Deal found 4/17$450
This Air Canada deal was found by Cheapflights users on 4/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/21:30 pmSTL - YYZ
1 stop7h 09mAir Canada
Wed 5/72:00 pmYYZ - STL
1 stop6h 58mAir Canada
Deal found 4/17$459
This Booking.com deal was found by Cheapflights users on 4/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/21:30 pmSTL - YUL
Nonstop2h 30mAir Canada
Sun 5/46:10 pmYUL - STL
Nonstop2h 48mAir Canada
Deal found 4/16$463
This United Airlines deal was found by Cheapflights users on 4/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/226:33 amSTL - YYZ
2 stops6h 46mUnited Airlines
Sat 7/262:10 pmYYZ - STL
Nonstop2h 06mUnited Airlines
Deal found 4/17$468
This Delta deal was found by Cheapflights users on 4/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/276:00 amSTL - YUL
1 stop9h 04mDelta
Wed 5/285:00 pmYUL - STL
1 stop16h 07mDelta
Deal found 4/16$470
This American Airlines deal was found by Cheapflights users on 4/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/116:04 amSTL - YUL
1 stop9h 41mAmerican Airlines
Tue 6/1712:30 pmYUL - STL
1 stop9h 00mAmerican Airlines
Deal found 4/16$489
This United Airlines deal was found by Cheapflights users on 4/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/288:15 amSTL - YUL
1 stop6h 34mUnited Airlines
Wed 5/286:10 pmYUL - STL
Nonstop2h 48mUnited Airlines
Deal found 4/16$508
This WestJet deal was found by Cheapflights users on 4/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure WestJet is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 6/66:00 amSTL - YYZ
2 stops23h 52mWestJet
Sun 6/86:30 amYYZ - STL
1 stop5h 02mWestJet
Deal found 4/16$510

Cheapflights Fare Finder

Customize your flight search to find flights from St. Louis to 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, Cheapflights users made 2,558,603 searches. Data last updated April 17, 2025.
Use the filters below to find and compare flights from St. Louis to Ontario that are best for you.

Fly from

St. Louis

Fly to

Ontario

Route

Depart

Return

Price

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 6/5

10:10 am-9:00 pm

1 stop9h 50m

Toronto Pearson Intl

Mon 6/9

4:00 pm-11:37 pm

1 stop8h 37m

$317

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

Sun 5/25

10:10 am-5:15 pm

1 stop30h 05m

Ottawa

Fri 5/30

3:50 pm-9:15 am

1 stop18h 25m

$340

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Thu 5/15

10:10 am-12:37 am

2 stops13h 27m

Montreal Pierre Elliott Trudeau Intl

Thu 5/22

6:45 am-11:52 pm

1 stop18h 07m

$413

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 5/8

6:00 am-2:30 pm

1 stop7h 30m

Toronto Pearson Intl

Mon 5/19

1:15 pm-11:51 pm

1 stop11h 36m

$435

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Mon 5/5

5:34 pm-11:15 pm

1 stop4h 41m

Toronto Pearson Intl

Tue 5/20

7:55 am-8:48 pm

1 stop13h 53m

$450

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 5/2

1:30 pm-9:39 pm

1 stop7h 09m

Toronto Pearson Intl

Wed 5/7

2:00 pm-7:58 pm

1 stop6h 58m

$459

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Fri 5/2

1:30 pm-5:00 pm

Nonstop2h 30m

Montreal Pierre Elliott Trudeau Intl

Sun 5/4

6:10 pm-7:58 pm

Nonstop2h 48m

$463

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Tue 7/22

6:33 am-2:19 pm

2 stops6h 46m

Toronto Pearson Intl

Sat 7/26

2:10 pm-3:16 pm

Nonstop2h 06m

$468

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Tue 5/27

6:00 am-4:04 pm

1 stop9h 04m

Montreal Pierre Elliott Trudeau Intl

Wed 5/28

5:00 pm-8:07 am

1 stop16h 07m

$470

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Wed 6/11

6:04 am-4:45 pm

1 stop9h 41m

Montreal Pierre Elliott Trudeau Intl

Tue 6/17

12:30 pm-8:30 pm

1 stop9h 00m

$489

Flights are sorted by cheapest round-trip flights first.

Deals found on 4/16

Showing 1-10 of 30 results
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2
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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
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

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, January is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of $243). Flying from St. Louis to Region of Ontario in July is currently the most expensive (average of $359). 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?

Find hourly flight availability from St. Louis to Ontario. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated April 17, 2025.

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.

Rainfall in Ontario by month

Plan your trip to Ontario by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Region of Ontario ranges from 2.0 - 3.3 inches per month. June is typically the wettest month, when rainfall can reach 3.3 in. February is typically the driest time to visit Region of Ontario when rainfall is around 2.0 in.

Temperature in Ontario by month

Plan your trip to Ontario by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Region of Ontario, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 69.8 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 21.2 F).

Reviews of airlines servicing Ontario

Get insights into the airlines that provide service to Ontario. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Ontario. Reviews last updated April 17, 2025.
Peruse reviews from past customers who have flown with Alaska Airlines, Delta and United Airlines from St. Louis to Ontario to help guide your decision. In addition to providing an overall rating, users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
9,882 reviews

Boarding

8.2

Crew

8.5

Food

7.1

Entertainment

7.1

Comfort

7.9

Overall

8.0

Reviews

1 / 20
4.0
Okay

Anonymous,Apr 2025

LAS - STS

flight was delayed both ways even tho the weather was clear >
Alaska Airlines
8.0
Very good
9,882 reviews
Alaska Airlines
8.0
Very good
9,882 reviews

Boarding

8.2

Crew

8.5

Food

7.1

Entertainment

7.1

Comfort

7.9

Overall

8.0

Reviews

1 / 20
4.0
Okay

Anonymous,Apr 2025

LAS - STS

flight was delayed both ways even tho the weather was clear >
Delta
8.0
Very good
7,917 reviews
Alaska Airlines
8.0
Very good
9,882 reviews

Boarding

8.2

Crew

8.5

Food

7.1

Entertainment

7.1

Comfort

7.9

Overall

8.0

Reviews

1 / 20
4.0
Okay

Anonymous,Apr 2025

LAS - STS

flight was delayed both ways even tho the weather was clear >
United Airlines
7.4
Good
8,667 reviews
Alaska Airlines
8.0
Very good
9,882 reviews

Boarding

8.2

Crew

8.5

Food

7.1

Entertainment

7.1

Comfort

7.9

Overall

8.0

Reviews

1 / 20
4.0
Okay

Anonymous,Apr 2025

LAS - STS

flight was delayed both ways even tho the weather was clear >
American Airlines
7.2
Good
10,000 reviews
Alaska Airlines
8.0
Very good
9,882 reviews

Boarding

8.2

Crew

8.5

Food

7.1

Entertainment

7.1

Comfort

7.9

Overall

8.0

Reviews

1 / 20
4.0
Okay

Anonymous,Apr 2025

LAS - STS

flight was delayed both ways even tho the weather was clear >
WestJet
7.2
Good
2,809 reviews
Alaska Airlines
8.0
Very good
9,882 reviews

Boarding

8.2

Crew

8.5

Food

7.1

Entertainment

7.1

Comfort

7.9

Overall

8.0

Reviews

1 / 20
4.0
Okay

Anonymous,Apr 2025

LAS - STS

flight was delayed both ways even tho the weather was clear >

Related info for your journey

Find useful and relevant information for your journey from St. Louis to Ontario. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

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

    Lambert-St Louis (STL) is the airport you will fly out of if you book a flight from St. Louis to Ontario. It is only a 12.7 mi journey to Lambert-St Louis (STL) from St. Louis’s city center.

  • What are the cheapest airlines to fly from St. Louis to Region of Ontario one-way?

    One-way options have recently been found by users for as low as $194 on American Airlines. Other airlines that offer cheap prices include Delta from $196 and Air Canada from $198 one-way.

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

    When deciding which route to take from St. Louis to Region of Ontario consider Lambert-St Louis - Montreal Pierre Elliott Trudeau Intl, Lambert-St Louis - Toronto Pearson Intl or Lambert-St Louis - Ottawa as they are the most popular.

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

    No one likes to see their flight delayed. When booking a flight from St. Louis to Region of Ontario consider choosing Air Canada (78%), Jazz (78%) or United Airlines (78%) as they are the most reliable in getting you off to your destination on time.

  • What are the cheapest flights from St. Louis to Region of Ontario?

    Looking for the cheapest flight from St. Louis to Region of Ontario? While on average our users pay $2,330, our data indicates the cheapest price to be $205. The most popular route (Lambert-St Louis - Montreal Pierre Elliott Trudeau Intl), is priced around $419.

  • 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, January is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of $243). Flying from St. Louis to Region of Ontario in July is currently the most expensive (average of $359). 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

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Alternative routes for St. Louis to Ontario

See prices for flight routes from nearby airports that may be better suited for you.
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Top 3 airlines flying from St. Louis to Ontario

Discover the top 3 airlines that operate flights from St. Louis to Ontario. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated April 17, 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapest$218Average$646FlexibilityNo cancel feeOn-time67%
United AirlinesCheapest$237Average$674FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$304Average$621FlexibilityNo cancel feeOn-time71%

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