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$128+ 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 4/8. Fares are subject to change and may not be available on all flights or dates of travel.
STL — YYZ
Apr 5 — Apr 121
Sat 4/5
Sat 4/12
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 March 31, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$292
(Kiwi.com)

One-way from

$128
(Kiwi.com)

Popular in

March

Cheapest in

May

Average price

$583

Good round-trip deal

$835 or less

Good one-way deal

$260 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. 5% potential increase in price ($24 potential increase over avg. RT price).
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Cheapest flight prices on average. 4% potential price decrease ($18 potential savings vs. average RT price).
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Average for round-trip flights in March 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 March 31, 2025.

This Kiwi.com deal was found by Cheapflights users on 3/31. 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 - YYZ
1 stop9h 50mMultiple Airlines
Thu 5/224:00 pmYYZ - STL
1 stop8h 52mMultiple Airlines
Deal found 3/31$292
This Mytrip deal was found by Cheapflights users on 3/30. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/69:50 amSTL - YOW
3 stops13h 32mMultiple Airlines
Wed 5/74:25 pmYOW - STL
2 stops17h 50mMultiple Airlines
Deal found 3/30$392
This American Airlines deal was found by Cheapflights users on 3/30. 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.
Sun 5/185:00 amSTL - YYZ
1 stop6h 30mAmerican Airlines
Sun 5/183:45 pmYYZ - STL
1 stop4h 38mAmerican Airlines
Deal found 3/30$465
This Delta deal was found by Cheapflights users on 3/30. 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 5/136:00 amSTL - YYZ
1 stop10h 59mDelta
Fri 5/237:21 pmYYZ - STL
1 stop5h 05mDelta
Deal found 3/30$473
This Air Canada deal was found by Cheapflights users on 3/30. 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 5/27:30 amSTL - YYZ
Nonstop1h 55mAir Canada
Sun 5/411:30 amYYZ - STL
Nonstop2h 06mAir Canada
Deal found 3/30$488
This United Airlines deal was found by Cheapflights users on 3/29. 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.
Thu 9/48:10 amSTL - YYZ
2 stops9h 27mUnited Airlines
Sun 9/72:10 pmYYZ - STL
Nonstop2h 06mUnited Airlines
Deal found 3/29$508
This Mytrip deal was found by Cheapflights users on 3/30. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/1710:10 amSTL - YUL
2 stops37h 27mMultiple Airlines
Wed 5/216:45 amYUL - STL
1 stop27h 30mMultiple Airlines
Deal found 3/30$516
This Justfly.com deal was found by Cheapflights users on 3/30. 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 Justfly.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 4/205:32 pmSTL - YYZ
1 stop5h 24mWestJet
Thu 4/249:45 amYYZ - STL
1 stop4h 16mWestJet
Deal found 3/30$524
This Delta deal was found by Cheapflights users on 3/30. 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.
Sat 5/176:00 amSTL - YUL
1 stop6h 41mDelta
Wed 5/216:05 amYUL - STL
1 stop10h 03mDelta
Deal found 3/30$554
This Air Canada deal was found by Cheapflights users on 3/31. 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.
Sun 6/151:30 pmSTL - YUL
Nonstop2h 30mAir Canada
Sat 6/216:10 pmYUL - STL
Nonstop2h 48mAir Canada
Deal found 3/31$582
This American Airlines deal was found by Cheapflights users on 3/30. 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.
Sun 5/187:10 amSTL - YUL
1 stop5h 34mAmerican Airlines
Sun 5/252:35 pmYUL - STL
1 stop5h 48mAmerican Airlines
Deal found 3/30$596
This United Airlines deal was found by Cheapflights users on 3/30. 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 5/146:30 amSTL - YUL
2 stops10h 55mUnited Airlines
Wed 5/216:10 pmYUL - STL
Nonstop2h 48mUnited Airlines
Deal found 3/30$601

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 March 31, 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 5/15

10:10 am-9:00 pm

1 stop9h 50m

Toronto Pearson Intl

Thu 5/22

4:00 pm-11:52 pm

1 stop8h 52m

$292

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

Tue 5/6

9:50 am-12:22 am

3 stops13h 32m

Ottawa

Wed 5/7

4:25 pm-9:15 am

2 stops17h 50m

$392

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Tue 4/22

12:55 pm-10:51 pm

1 stop8h 56m

Toronto Pearson Intl

Wed 4/30

6:15 am-2:46 pm

1 stop9h 31m

$462

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sun 5/18

5:00 am-12:30 pm

1 stop6h 30m

Toronto Pearson Intl

Sun 5/18

3:45 pm-7:23 pm

1 stop4h 38m

$465

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 5/2

7:30 am-10:25 am

Nonstop1h 55m

Toronto Pearson Intl

Sun 5/4

11:30 am-12:36 pm

Nonstop2h 06m

$488

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 9/4

8:10 am-6:37 pm

2 stops9h 27m

Toronto Pearson Intl

Sun 9/7

2:10 pm-3:16 pm

Nonstop2h 06m

$508

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Sat 5/17

10:10 am-12:37 am

2 stops37h 27m

Montreal Pierre Elliott Trudeau Intl

Wed 5/21

6:45 am-9:15 am

1 stop27h 30m

$516

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sun 4/27

6:50 am-11:25 am

1 stop3h 35m

Toronto Pearson Intl

Sun 5/4

6:08 pm-9:36 pm

1 stop4h 28m

$521

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Sat 5/17

6:00 am-1:41 pm

1 stop6h 41m

Montreal Pierre Elliott Trudeau Intl

Wed 5/21

6:05 am-3:08 pm

1 stop10h 03m

$554

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Sun 6/15

1:30 pm-5:00 pm

Nonstop2h 30m

Montreal Pierre Elliott Trudeau Intl

Sat 6/21

6:10 pm-7:58 pm

Nonstop2h 48m

$582

Flights are sorted by cheapest round-trip flights first.

Deals found on 3/30

Showing 1-10 of 28 results
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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 March 31, 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 March 31, 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
9,818 reviews

Boarding

8.2

Crew

8.5

Food

7.1

Comfort

7.9

Overall

8.0

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
Alaska Airlines
8.0
Very good
9,818 reviews
Alaska Airlines
8.0
Very good
9,818 reviews

Boarding

8.2

Crew

8.5

Food

7.1

Comfort

7.9

Overall

8.0

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
Delta
8.0
Very good
7,899 reviews
Alaska Airlines
8.0
Very good
9,818 reviews

Boarding

8.2

Crew

8.5

Food

7.1

Comfort

7.9

Overall

8.0

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
United Airlines
7.4
Good
8,614 reviews
Alaska Airlines
8.0
Very good
9,818 reviews

Boarding

8.2

Crew

8.5

Food

7.1

Comfort

7.9

Overall

8.0

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
American Airlines
7.2
Good
10,000 reviews
Alaska Airlines
8.0
Very good
9,818 reviews

Boarding

8.2

Crew

8.5

Food

7.1

Comfort

7.9

Overall

8.0

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
WestJet
7.2
Good
2,789 reviews
Alaska Airlines
8.0
Very good
9,818 reviews

Boarding

8.2

Crew

8.5

Food

7.1

Comfort

7.9

Overall

8.0

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them

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 $191 on Delta. Other airlines that offer cheap prices include Air Canada from $213 and United Airlines from $229 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 - Toronto Pearson Intl, Lambert-St Louis - Montreal Pierre Elliott Trudeau 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 (71%), Jazz (71%) or United Airlines (71%) 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 $2,375, our data indicates the cheapest price to be $214. The most popular route (Lambert-St Louis - Toronto Pearson Intl), is priced around $321.

  • 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 March 31, 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapest$223Average$652FlexibilityNo cancel feeOn-time67%
United AirlinesCheapest$237Average$675FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$304Average$590FlexibilityNo cancel feeOn-time71%
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