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St. Louis

$160+ Cheap flights from Ontario to St. Louis (STL)

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 7/15. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — STL
juin 17 — juin 241
mar. 6/17
mar. 6/24
1 adult, Economy
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Cheap flight deals from Ontario to St. Louis

Keep the following information in mind while searching for Ontario to St. Louis flight deals. Data was last updated juin 12, 2025.

Round-trip from

$333
(American Airlines)

One-way from

$160
(Mytrip)

Popular in

August

Cheapest in

June

Average price

$390

Good round-trip deal

$324 or less

Good one-way deal

$188 or less
From Ontario to Lambert-St Louis
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One-way flight from Ontario to Lambert-St Louis
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Highest demand for flights based on searches. 5% potential increase in price ($29 potential increase over avg. RT price).
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Cheapest flight prices on average. 1% potential price decrease ($8 potential savings vs. average RT price).
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Average for round-trip flights in June 2025
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Price to beat on a round-trip flight from Ontario to Lambert-St Louis.
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Price to beat on a one-way flight from Ontario to Lambert-St Louis.
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Find flight deals from Ontario to St. Louis

Cheapest flights from Ontario to St. Louis
Explore the most affordable flight options available from Ontario to St. Louis. Find the lowest fares from popular airlines and budget airlines, with prices last updated on juin 12, 2025.

This American Airlines deal was found by Cheapflights users on 6/11. 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.
jeu. 9/2512:30 pmYUL - STL
1 stop8h 55mAmerican Airlines
lun. 9/295:55 amSTL - YUL
1 stop9h 35mAmerican Airlines
Deal found 6/11$333
This Mytrip deal was found by Cheapflights users on 6/12. 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.
mar. 7/226:30 amYYZ - STL
1 stop11h 01mMultiple Airlines
jeu. 7/2410:47 amSTL - YYZ
2 stops33h 36mMultiple Airlines
Deal found 6/12$337
This American Airlines deal was found by Cheapflights users on 6/10. 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.
lun. 6/237:25 pmYYZ - STL
1 stop5h 34mAmerican Airlines
jeu. 6/266:00 amSTL - YYZ
1 stop3h 59mAmerican Airlines
Deal found 6/10$339
This Booking.com deal was found by Cheapflights users on 6/11. 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.
jeu. 6/2611:30 amYYZ - STL
Nonstop2h 06mAir Canada
dim. 6/291:30 pmSTL - YYZ
1 stop15h 55mAir Canada
Deal found 6/11$344
This Delta deal was found by Cheapflights users on 6/10. 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.
ven. 6/202:27 pmYYZ - STL
1 stop7h 26mDelta
dim. 6/227:00 amSTL - YYZ
1 stop9h 06mDelta
Deal found 6/10$361
This United Airlines deal was found by Cheapflights users on 6/12. 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.
lun. 10/69:00 amYYZ - STL
1 stop26h 49mUnited Airlines
jeu. 10/912:25 pmSTL - YYZ
1 stop7h 37mUnited Airlines
Deal found 6/12$363
This Mytrip deal was found by Cheapflights users on 6/12. 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.
jeu. 7/101:10 pmYUL - STL
2 stops21h 42mMultiple Airlines
jeu. 7/1710:47 amSTL - YUL
3 stops26h 03mMultiple Airlines
Deal found 6/12$393
This Delta deal was found by Cheapflights users on 6/11. 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.
jeu. 8/286:00 amYUL - STL
2 stops11h 06mDelta
mar. 9/212:00 pmSTL - YUL
1 stop8h 48mDelta
Deal found 6/11$458
This Air Canada deal was found by Cheapflights users on 6/10. 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.
lun. 6/238:00 amYUL - STL
1 stop5h 36mAir Canada
dim. 6/291:30 pmSTL - YUL
Nonstop2h 30mAir Canada
Deal found 6/10$470
This FlightHub deal was found by Cheapflights users on 6/10. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
ven. 8/2910:12 amYYZ - STL
1 stop4h 08mWestJet
dim. 9/76:00 amSTL - YYZ
2 stops11h 03mWestJet
Deal found 6/10$490
This United Airlines deal was found by Cheapflights users on 6/12. 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.
jeu. 6/194:30 pmYUL - STL
1 stop5h 45mUnited Airlines
jeu. 6/268:00 amSTL - YUL
1 stop8h 26mUnited Airlines
Deal found 6/12$536
This United Airlines deal was found by Cheapflights users on 6/11. 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.
mer. 7/95:25 pmYOW - STL
1 stop5h 10mUnited Airlines
mer. 7/165:00 amSTL - YOW
1 stop15h 35mUnited Airlines
Deal found 6/11$584

Cheapflights Fare Finder

Customize your flight search to find flights from 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, Cheapflights users made 2,558,603 searches. Data last updated juin 12, 2025.
Use the filters below to find and compare flights from Ontario to St. Louis that are best for you.

Fly from

Ontario

Fly to

St. Louis

Route

Depart

Return

Price

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

jeu. 9/25

12:30 pm-8:25 pm

1 stop8h 55m

Lambert-St Louis

lun. 9/29

5:55 am-4:30 pm

1 stop9h 35m

$333

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

mar. 7/22

6:30 am-4:31 pm

1 stop11h 01m

Lambert-St Louis

jeu. 7/24

10:47 am-9:23 pm

2 stops33h 36m

$337

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

lun. 6/23

7:25 pm-11:59 pm

1 stop5h 34m

Lambert-St Louis

jeu. 6/26

6:00 am-10:59 am

1 stop3h 59m

$339

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

jeu. 6/26

11:30 am-12:36 pm

Nonstop2h 06m

Lambert-St Louis

dim. 6/29

1:30 pm-6:25 am

1 stop15h 55m

$344

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

jeu. 6/26

10:20 am-3:17 pm

1 stop5h 57m

Lambert-St Louis

dim. 6/29

6:40 am-11:18 am

1 stop3h 38m

$361

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

lun. 10/6

9:00 am-10:49 am

1 stop26h 49m

Lambert-St Louis

jeu. 10/9

12:25 pm-9:02 pm

1 stop7h 37m

$363

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

jeu. 7/10

1:10 pm-9:52 am

2 stops21h 42m

Lambert-St Louis

jeu. 7/17

10:47 am-1:50 pm

3 stops26h 03m

$393

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

jeu. 8/28

6:00 am-4:06 pm

2 stops11h 06m

Lambert-St Louis

mar. 9/2

12:00 pm-9:48 pm

1 stop8h 48m

$458

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

lun. 6/23

8:00 am-12:36 pm

1 stop5h 36m

Lambert-St Louis

dim. 6/29

1:30 pm-5:00 pm

Nonstop2h 30m

$470

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

ven. 8/29

10:12 am-1:20 pm

1 stop4h 08m

Lambert-St Louis

dim. 9/7

6:00 am-6:03 pm

2 stops11h 03m

$490

Flights are sorted by cheapest round-trip flights first.

Deals found on 6/11

Showing 1-10 of 26 results
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Best time to book a flight from Ontario to St. Louis

Have a flexible travel schedule? Discover the best time to fly to St. Louis from Ontario 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 Ontario to St. Louis

What is the cheapest month to book a flight from Region of Ontario to St. Louis?

Currently, August is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of $311). Flying from Region of Ontario to St. Louis in March is currently the most expensive (average of $356). 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 ON to STL?

Find hourly flight availability from Ontario to St. Louis. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated juin 12, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Region of Ontario to St. Louis as you normally would.

Weekly flight availability from Region of Ontario to St. Louis

Explore weekly flight availability from Ontario to St. Louis. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated juin 12, 2025.

The most flights from CAON to STL are scheduled on a Wednesday (4 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (3 on average).

Rainfall in St. Louis by month

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

In terms of precipitation, rainfall in St. Louis ranges from 2.2 - 4.7 inches per month. May is typically the wettest month, when rainfall can reach 4.7 in. February is typically the driest time to visit St. Louis when rainfall is around 2.2 in.

Temperature in St. Louis by month

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

If weather is an important factor for your trip to St. Louis, 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 80.6 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 32.0 F).

Reviews of airlines servicing St. Louis

Get insights into the airlines that provide service to St. Louis. 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 St. Louis. Reviews last updated juin 12, 2025.
Peruse reviews from past customers who have flown with Delta, United Airlines and American Airlines from Ontario to St. Louis to help guide your decision. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Delta
8.0
Very good
7,950 reviews

Boarding

8.2

Food

7.3

Crew

8.5

Comfort

7.9

Overall

8.0

Entertainment

7.9

Reviews

1 / 20
10.0
Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!
Delta
8.0
Very good
7,950 reviews
Delta
8.0
Very good
7,950 reviews

Boarding

8.2

Food

7.3

Crew

8.5

Comfort

7.9

Overall

8.0

Entertainment

7.9

Reviews

1 / 20
10.0
Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!
United Airlines
7.4
Good
8,790 reviews
Delta
8.0
Very good
7,950 reviews

Boarding

8.2

Food

7.3

Crew

8.5

Comfort

7.9

Overall

8.0

Entertainment

7.9

Reviews

1 / 20
10.0
Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!
American Airlines
7.2
Good
10,000 reviews
Delta
8.0
Very good
7,950 reviews

Boarding

8.2

Food

7.3

Crew

8.5

Comfort

7.9

Overall

8.0

Entertainment

7.9

Reviews

1 / 20
10.0
Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!
WestJet
7.2
Good
2,868 reviews
Delta
8.0
Very good
7,950 reviews

Boarding

8.2

Food

7.3

Crew

8.5

Comfort

7.9

Overall

8.0

Entertainment

7.9

Reviews

1 / 20
10.0
Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!
Air Canada
7.1
Good
9,531 reviews
Delta
8.0
Very good
7,950 reviews

Boarding

8.2

Food

7.3

Crew

8.5

Comfort

7.9

Overall

8.0

Entertainment

7.9

Reviews

1 / 20
10.0
Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!

Related info for your journey

Find useful and relevant information for your journey from Ontario to St. Louis. 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 into for flights to St. Louis from Ontario?

    Located just 12.7 mi from the city center, Lambert-St Louis (STL) is the airport most travelers will use when flying to St. Louis from Ontario.

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

    $188 is the cheapest one-way deal found within the past few days, from Air Canada. You may also be able to find cheap deals on American Airlines and United Airlines, with prices starting from $198 and $220, respectively.

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

    While some choose either Montreal Pierre Elliott Trudeau Intl - Lambert-St Louis or Ottawa - Lambert-St Louis, Toronto Pearson Intl - Lambert-St Louis is the most popular route from Region of Ontario to St. Louis.

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

    Looking for the most reliable airlines to get you to your destination on time? Our data shows these are most likely to get you from Region of Ontario to St. Louis on time: Jazz (83%), Air Canada (77%), United Airlines (50%).

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

    The cheapest flight price from Region of Ontario to St. Louis is $187. On average you can expect to pay $379. The most popular route, (Toronto Pearson Intl - Lambert-St Louis), can usually be booked for $330.

  • Can I find deals for flights from Ontario to St. Louis that include hotel bookings?

    Yes. In addition to deals on Ontario to St. Louis flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Ontario to St. Louis?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Ontario to St. Louis.

  • Can I find deals for business class flights from Ontario to St. Louis?

    Yes. Cheapflights offers flight deals from Ontario to St. Louis 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 Region of Ontario to St. Louis?

    Currently, August is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of $311). Flying from Region of Ontario to St. Louis in March is currently the most expensive (average of $356). 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

Traveling to a place near Ontario?

Book flights to Ontario if you plan to visit one of these locations
O'Fallon
Maryland Heights
Fairview Heights
Collinsville
Eureka
St. Peters
Glencoe
Festus
Alton
Farmington

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Alternative routes for Ontario to St. Louis

See prices for flight routes from nearby airports that may be better suited for you.
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Top 2 airlines flying from Ontario to St. Louis

Discover the top 2 airlines that operate flights from Ontario to St. Louis. 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 juin 12, 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapest$324Average$476FlexibilityNo cancel feeOn-time67%
United AirlinesCheapest$371Average$499FlexibilityNo cancel feeOn-time69%

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