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St. Louis

$151+ 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 4/29. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — STL
Apr 7 — Apr 141
Mon 4/7
Mon 4/14
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 April 2, 2025.

Round-trip from

$372
(Kiwi.com)

One-way from

$151
(Kiwi.com)

Popular in

January

Cheapest in

May

Average price

$491

Good round-trip deal

$417 or less

Good one-way deal

$261 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. 4% potential increase in price ($23 potential increase over avg. RT price).
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Cheapest flight prices on average. 0% potential price decrease ($5 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 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 April 2, 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 4/1011:10 amYYZ - STL
1 stop13h 36mMultiple Airlines
Fri 5/99:50 amSTL - YYZ
2 stops10h 18mMultiple Airlines
Deal found 3/31$372
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.
Thu 5/16:30 pmYYZ - STL
Nonstop2h 13mAir Canada
Wed 5/77:30 amSTL - YYZ
Nonstop1h 55mAir Canada
Deal found 3/31$379
This CheapTicketsDeal deal was found by Cheapflights users on 4/1. 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 CheapTicketsDeal is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/2110:20 amYYZ - STL
1 stop5h 48mWestJet
Tue 5/276:00 amSTL - YYZ
1 stop6h 40mWestJet
Deal found 4/1$389
This United Airlines 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/65:15 pmYYZ - STL
1 stop6h 30mUnited Airlines
Tue 9/29:17 amSTL - YYZ
1 stop6h 26mUnited Airlines
Deal found 3/31$398
This Delta deal was found by Cheapflights users on 4/1. 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.
Sun 9/216:15 amYYZ - STL
1 stop5h 56mDelta
Thu 9/256:45 amSTL - YYZ
1 stop7h 33mDelta
Deal found 4/1$399
This American Airlines deal was found by Cheapflights users on 4/1. 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 5/13:45 pmYYZ - STL
1 stop6h 39mAmerican Airlines
Sun 5/45:00 amSTL - YYZ
1 stop5h 05mAmerican Airlines
Deal found 4/1$400
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 5/16:45 amYUL - STL
1 stop18h 21mMultiple Airlines
Wed 5/75:45 pmSTL - YUL
1 stop19h 35mMultiple Airlines
Deal found 3/31$412
This Kiwi.com deal was found by Cheapflights users on 4/1. 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.
Tue 4/159:20 amYOW - STL
1 stop8h 55mMultiple Airlines
Thu 5/810:10 amSTL - YOW
2 stops13h 12mMultiple Airlines
Deal found 4/1$415
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.
Thu 5/16:10 pmYUL - STL
Nonstop2h 48mAir Canada
Thu 5/81:30 pmSTL - YUL
Nonstop2h 30mAir Canada
Deal found 3/31$447
This Delta deal was found by Cheapflights users on 4/1. 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.
Wed 5/75:05 pmYUL - STL
1 stop4h 44mDelta
Wed 5/142:15 pmSTL - YUL
1 stop8h 01mDelta
Deal found 4/1$456
This United Airlines 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/16:10 pmYUL - STL
Nonstop2h 48mUnited Airlines
Thu 5/88:25 amSTL - YUL
1 stop7h 50mUnited Airlines
Deal found 3/31$458
This American Airlines deal was found by Cheapflights users on 4/1. 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.
Mon 4/282:30 pmYUL - STL
1 stop5h 53mAmerican Airlines
Wed 4/306:15 amSTL - YUL
2 stops9h 30mAmerican Airlines
Deal found 4/1$506

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 April 2, 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

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Fri 4/11

8:00 pm-5:43 pm

1 stop22h 43m

Lambert-St Louis

Mon 5/5

9:55 pm-5:20 pm

1 stop18h 25m

$373

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Thu 5/1

6:30 pm-7:43 pm

Nonstop2h 13m

Lambert-St Louis

Sun 5/4

1:30 pm-9:39 pm

1 stop7h 09m

$378

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 5/21

10:20 am-3:08 pm

1 stop5h 48m

Lambert-St Louis

Tue 5/27

6:00 am-1:40 pm

1 stop6h 40m

$389

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 8/6

5:15 pm-10:45 pm

1 stop6h 30m

Lambert-St Louis

Tue 9/2

9:17 am-4:43 pm

1 stop6h 26m

$398

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sun 9/21

6:15 am-11:11 am

1 stop5h 56m

Lambert-St Louis

Thu 9/25

6:45 am-3:18 pm

1 stop7h 33m

$399

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Thu 5/1

3:45 pm-9:24 pm

1 stop6h 39m

Lambert-St Louis

Sun 5/4

5:00 am-11:05 am

1 stop5h 05m

$400

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Thu 5/1

6:45 am-12:06 am

1 stop18h 21m

Lambert-St Louis

Wed 5/7

5:45 pm-2:20 pm

1 stop19h 35m

$412

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Tue 4/15

9:20 am-5:15 pm

1 stop8h 55m

Lambert-St Louis

Thu 5/8

10:10 am-12:22 am

2 stops13h 12m

$415

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Thu 5/1

6:10 pm-7:58 pm

Nonstop2h 48m

Lambert-St Louis

Thu 5/8

1:30 pm-5:00 pm

Nonstop2h 30m

$447

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Wed 5/7

5:05 pm-8:49 pm

1 stop4h 44m

Lambert-St Louis

Wed 5/14

2:15 pm-11:16 pm

1 stop8h 01m

$456

Flights are sorted by cheapest round-trip flights first.

Deals found on 3/31

Showing 1-10 of 33 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 April 2, 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 April 2, 2025.

The most flights from CAON to STL are scheduled on a Tuesday (2 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (1 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 April 2, 2025.
Peruse reviews from past customers who have flown with Alaska Airlines, Delta and United 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.
Alaska Airlines
8.0
Very good
9,820 reviews

Boarding

8.2

Entertainment

7.1

Overall

8.0

Comfort

7.9

Crew

8.5

Food

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
9,820 reviews
Alaska Airlines
8.0
Very good
9,820 reviews

Boarding

8.2

Entertainment

7.1

Overall

8.0

Comfort

7.9

Crew

8.5

Food

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
7,898 reviews
Alaska Airlines
8.0
Very good
9,820 reviews

Boarding

8.2

Entertainment

7.1

Overall

8.0

Comfort

7.9

Crew

8.5

Food

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
8,615 reviews
Alaska Airlines
8.0
Very good
9,820 reviews

Boarding

8.2

Entertainment

7.1

Overall

8.0

Comfort

7.9

Crew

8.5

Food

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
9,820 reviews

Boarding

8.2

Entertainment

7.1

Overall

8.0

Comfort

7.9

Crew

8.5

Food

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
9,820 reviews

Boarding

8.2

Entertainment

7.1

Overall

8.0

Comfort

7.9

Crew

8.5

Food

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 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?

    $220 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 Delta and United Airlines, with prices starting from $227 and $237, 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: Air Canada (79%), Jazz (79%), United Airlines (79%).

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

    The cheapest flight price from Region of Ontario to St. Louis is $214. On average you can expect to pay $473. The most popular route, (Toronto Pearson Intl - Lambert-St Louis), can usually be booked for $293.

  • 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
Fenton
Maryland Heights
Fairview Heights
Collinsville
Wentzville
Eureka
St. Peters
Festus
Glencoe
Alton
Farmington
Chesterfield

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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 April 2, 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapest$361Average$571FlexibilityNo cancel feeOn-time67%
United AirlinesCheapest$371Average$573FlexibilityNo cancel feeOn-time69%

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