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

For one-way options, check prices for American Airlines. According to our data, you can fly for as low as C$ 193. Users have also found prices from C$ 209 and C$ 246 on Sun Country Air and Delta, respectively.

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

The most popular flight routes from St. Louis to Region of Ontario are Lambert-St Louis - Toronto Pearson Intl, Lambert-St Louis - Montreal Pierre Elliott Trudeau Intl and Lambert-St Louis - London.

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

The cheapest flight price from St. Louis to Region of Ontario is C$ 507. On average you can expect to pay C$ 586. The most popular route, (Lambert-St Louis - Toronto Pearson Intl), can usually be booked for C$ 427.

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

Before booking your flight to Region of Ontario from St. Louis, check out the most reliable airlines to get you to your destination on time: United Airlines (73%), Air Canada (50%), Jazz( 37%).

How far in advance should I book a flight from St. Louis to Region of Ontario?

When searching for a good deal, it’s best to be prepared for potential fluctuations in price. We recommend booking at least 53 days in advance, which can save you up to 399% on flights from St. Louis to Region of Ontario compared to booking the week you need them. Waiting 53 days out may not be for everyone, so we have options available for flights within the next two weeks, with the lowest price starting at C$ 429. For sooner than that we have options available in the next 3 days from C$ 1,243.

What is the cheapest month to fly from St. Louis to Region of Ontario?

January is one of the best times of the year to fly to Region of Ontario from St. Louis. Prices for January average C$ 580 per person but you can even find prices for as low as C$ 339. The most expensive prices can be found in the month of March. Opting for a January flight can save you 37% on your journey compared to booking in March

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

If you book a flight to Ontario from St. Louis, you will be flying from Lambert-St Louis, which is the city’s only airport. Lambert-St Louis (STL) is located 20.4 km from the centre of St. Louis.

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.

C$ 193+ Flights from St. Louis to Ontario

Cheap flight deals from St. Louis to Ontario

Round-trip from	C$ 413
One-way from	C$ 193
Popular in	March
Cheapest in	January
Average price	C$ 543
Good round-trip deal	C$ 574 or less

9/7-15/7
3 total stops
36h 42m total
St. Louis to Ontario

Search Deals

American Airlines
25/9
1 total stop
10h 54m total
St. Louis to Ontario

Search Deals

High demand for flights, 2% potential price rise

Search Deals

Cheapest flight prices on average. 3% potential price decrease (C$ 28 potential savings vs. average RT price).

Search Deals

Average for round-trip flights in June 2025

Search Deals

Price to beat on a round-trip flight from Lambert-St Louis to Ontario.

Search Deals

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 12 June 2025.

Wed 9/711:24 a.m.STL - YYZ

2 stops25h 41mMultiple Airlines

Tue 15/76:30 a.m.YYZ - STL

1 stop11h 01mMultiple Airlines

Deal found 10/6C$ 413

Mon 15/95:55 a.m.STL - YYZ

1 stop10h 54mAmerican Airlines

Wed 17/911:44 a.m.YYZ - STL

1 stop11h 09mAmerican Airlines

Deal found 11/6C$ 461

Thu 18/97:23 a.m.STL - YUL

1 stop8h 07mAmerican Airlines

Tue 23/95:15 p.m.YUL - STL

1 stop17h 11mAmerican Airlines

Deal found 11/6C$ 465

Sun 29/66:12 a.m.STL - YYZ

1 stop9h 38mSun Country Air

Thu 3/711:40 a.m.YYZ - STL

1 stop24h 50mSun Country Air

Deal found 9/6C$ 495

Sun 22/67:30 a.m.STL - YYZ

Nonstop1h 55mAir Canada

Thu 26/611:30 a.m.YYZ - STL

Nonstop2h 06mAir Canada

Deal found 10/6C$ 509

Fri 20/65:20 a.m.STL - YYZ

1 stop8h 51mUnited Airlines

Fri 20/65:15 p.m.YYZ - STL

1 stop6h 30mUnited Airlines

Deal found 10/6C$ 510

Fri 20/66:40 a.m.STL - YYZ

1 stop7h 01mDelta

Sat 21/63:31 p.m.YYZ - STL

1 stop5h 59mDelta

Deal found 10/6C$ 543

Mon 14/710:47 a.m.STL - YUL

2 stops30h 08mMultiple Airlines

Mon 21/78:55 a.m.YUL - STL

3 stops32h 36mMultiple Airlines

Deal found 10/6C$ 550

Mon 11/86:45 p.m.STL - YUL

1 stop14h 22mDelta

Tue 19/86:00 a.m.YUL - STL

1 stop15h 57mDelta

Deal found 12/6C$ 604

Mon 11/85:30 p.m.STL - YUL

1 stop17h 28mUnited Airlines

Tue 12/83:30 p.m.YUL - STL

2 stops19h 29mUnited Airlines

Deal found 12/6C$ 749

Tue 24/61:30 p.m.STL - YUL

Nonstop2h 30mAir Canada

Wed 25/67:00 a.m.YUL - STL

1 stop6h 36mAir Canada

Deal found 10/6C$ 800

Tue 5/81:42 p.m.STL - YXU

2 stops26h 25mUnited Airlines

Tue 12/83:35 p.m.YXU - STL

2 stops22h 11mUnited Airlines

Deal found 10/6C$ 932

Best flights from St. Louis to Ontario
Discover carefully curated flight deals from St. Louis to Ontario that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated 12 June 2025.

Wed 9/711:24 a.m.STL - YYZ

2 stops25h 41mMultiple Airlines

Tue 15/76:30 a.m.YYZ - STL

1 stop11h 01mMultiple Airlines

Deal found 10/6C$ 413

Mon 15/95:55 a.m.STL - YYZ

1 stop10h 54mAmerican Airlines

Wed 17/911:44 a.m.YYZ - STL

1 stop11h 09mAmerican Airlines

Deal found 11/6C$ 461

Sun 29/66:12 a.m.STL - YYZ

1 stop9h 38mSun Country Air

Thu 3/711:40 a.m.YYZ - STL

1 stop24h 50mSun Country Air

Deal found 9/6C$ 495

Sun 22/67:30 a.m.STL - YYZ

Nonstop1h 55mAir Canada

Thu 26/611:30 a.m.YYZ - STL

Nonstop2h 06mAir Canada

Deal found 10/6C$ 509

Thu 25/912:25 p.m.STL - YYZ

1 stop7h 37mUnited Airlines

Sun 28/92:10 p.m.YYZ - STL

1 stop25h 17mUnited Airlines

Deal found 10/6C$ 539

Mon 11/86:45 p.m.STL - YUL

1 stop14h 22mDelta

Tue 19/86:00 a.m.YUL - STL

1 stop15h 57mDelta

Deal found 12/6C$ 604

Thu 18/97:23 a.m.STL - YUL

1 stop8h 07mAmerican Airlines

Tue 23/95:15 p.m.YUL - STL

1 stop17h 11mAmerican Airlines

Deal found 11/6C$ 465

Mon 14/710:47 a.m.STL - YUL

2 stops30h 08mMultiple Airlines

Mon 21/78:55 a.m.YUL - STL

3 stops32h 36mMultiple Airlines

Deal found 10/6C$ 550

Fri 27/66:40 a.m.STL - YYZ

1 stop7h 01mDelta

Tue 22/76:05 p.m.YYZ - STL

1 stop3h 31mDelta

Deal found 11/6C$ 681

Mon 11/85:30 p.m.STL - YUL

1 stop17h 28mUnited Airlines

Tue 12/83:30 p.m.YUL - STL

2 stops19h 29mUnited Airlines

Deal found 12/6C$ 749

Tue 24/61:30 p.m.STL - YUL

Nonstop2h 30mAir Canada

Wed 25/67:00 a.m.YUL - STL

1 stop6h 36mAir Canada

Deal found 10/6C$ 800

Tue 5/81:42 p.m.STL - YXU

2 stops26h 25mUnited Airlines

Tue 12/83:35 p.m.YXU - STL

2 stops22h 11mUnited Airlines

Deal found 10/6C$ 932

Direct flights from St. Louis to Ontario
Explore direct flight options from St. Louis to Ontario based on user searches, and compare prices and availability for your desired travel dates. Data last updated 12 June 2025.

Sun 22/67:30 a.m.STL - YYZ

Nonstop1h 55mAir Canada

Thu 26/611:30 a.m.YYZ - STL

Nonstop2h 06mAir Canada

Deal found 10/6C$ 509

Fri 1/89:15 a.m.STL - YYZ

Nonstop2h 00mUnited Airlines

Sun 3/82:15 p.m.YYZ - STL

Nonstop2h 06mUnited Airlines

Deal found 10/6C$ 770

Sun 29/61:30 p.m.STL - YUL

Nonstop2h 30mAir Canada

Mon 21/76:10 p.m.YUL - STL

Nonstop2h 50mAir Canada

Deal found 11/6C$ 870

Sun 20/71:30 p.m.STL - YUL

Nonstop2h 30mUnited Airlines

Mon 21/76:10 p.m.YUL - STL

Nonstop2h 50mUnited Airlines

Deal found 12/6C$ 1,060

Fri 11/79:15 a.m.STL - YYZ

Nonstop2h 00mMultiple Airlines

Sun 27/76:35 p.m.YYZ - STL

Nonstop2h 10mMultiple Airlines

Deal found 9/6C$ 1,479

Last-minute flights from St. Louis to Ontario
Discover last-minute flight deals from St. Louis to Ontario. Data last updated 12 June 2025 and is based on user searches.

Tue 17/69:50 a.m.STL - YYZ

2 stops10h 18mMultiple Airlines

Sat 21/611:39 a.m.YYZ - STL

1 stop5h 46mMultiple Airlines

Deal found 10/6C$ 589

Wed 18/66:30 a.m.STL - YYZ

2 stops10h 34mWestJet

Wed 25/61:28 p.m.YYZ - STL

1 stop6h 16mWestJet

Deal found 12/6C$ 1,463

Wed 18/63:24 p.m.STL - YYZ

2 stops18h 35mAlaska Airlines

Fri 20/65:15 p.m.YYZ - STL

2 stops31h 44mAlaska Airlines

Deal found 11/6C$ 2,413

Fri 20/65:20 a.m.STL - YYZ

1 stop8h 51mUnited Airlines

Fri 20/65:15 p.m.YYZ - STL

1 stop6h 30mUnited Airlines

Deal found 10/6C$ 510

Fri 20/66:40 a.m.STL - YYZ

1 stop7h 01mDelta

Sat 21/63:31 p.m.YYZ - STL

1 stop5h 59mDelta

Deal found 10/6C$ 543

Sun 22/67:30 a.m.STL - YYZ

Nonstop1h 55mAir Canada

Thu 26/611:30 a.m.YYZ - STL

Nonstop2h 06mAir Canada

Deal found 10/6C$ 509

Sun 22/67:20 a.m.STL - YYZ

1 stop6h 10mAmerican Airlines

Thu 26/63:29 p.m.YYZ - STL

1 stop6h 26mAmerican Airlines

Deal found 10/6C$ 595

Tue 24/61:30 p.m.STL - YUL

Nonstop2h 30mAir Canada

Wed 25/67:00 a.m.YUL - STL

1 stop6h 36mAir Canada

Deal found 10/6C$ 800

Sun 29/66:12 a.m.STL - YYZ

1 stop9h 38mSun Country Air

Thu 3/711:40 a.m.YYZ - STL

1 stop24h 50mSun Country Air

Deal found 9/6C$ 495

Tue 1/76:00 a.m.STL - YUL

1 stop9h 07mDelta

Fri 4/76:00 a.m.YUL - STL

1 stop10h 17mDelta

Deal found 10/6C$ 664

Tue 1/75:00 a.m.STL - YUL

2 stops13h 45mUnited Airlines

Fri 4/78:30 a.m.YUL - STL

2 stops12h 01mUnited Airlines

Deal found 10/6C$ 860

Wed 9/711:24 a.m.STL - YYZ

2 stops25h 41mMultiple Airlines

Tue 15/76:30 a.m.YYZ - STL

1 stop11h 01mMultiple Airlines

Deal found 10/6C$ 413

One-way flights from St. Louis to Ontario
Search for one-way flight options from St. Louis to Ontario. Find affordable one-way fares based on user searches. Data last updated 12 June 2025.

Thu 25/95:55 a.m.STL - YYZ

1 stop10h 54mAmerican Airlines

Deal found 11/6C$ 193

Thu 18/97:23 a.m.STL - YUL

1 stop8h 07mAmerican Airlines

Deal found 11/6C$ 193

Thu 24/710:47 a.m.STL - YYZ

2 stops33h 36mMultiple Airlines

Deal found 12/6C$ 202

Thu 18/98:44 a.m.STL - YUL

2 stops32h 11mMultiple Airlines

Deal found 11/6C$ 206

Sun 6/76:36 a.m.STL - YYZ

1 stop9h 14mSun Country Air

Deal found 11/6C$ 209

Tue 14/1012:00 p.m.STL - YUL

1 stop8h 26mDelta

Deal found 12/6C$ 246

Sun 2/114:15 p.m.STL - YYZ

Nonstop1h 55mAir Canada

Deal found 12/6C$ 280

Sun 2/115:45 a.m.STL - YYZ

2 stops6h 29mUnited Airlines

Deal found 11/6C$ 302

Sun 29/61:30 p.m.STL - YUL

Nonstop2h 30mAir Canada

Deal found 12/6C$ 355

Sat 28/66:33 a.m.STL - YUL

2 stops7h 27mUnited Airlines

Deal found 10/6C$ 357

Fri 15/87:29 p.m.STL - YXU

2 stops32h 45mMultiple Airlines

Deal found 9/6C$ 407

Wed 6/81:42 p.m.STL - YXU

2 stops24h 15mUnited Airlines

Deal found 10/6C$ 443

Cheapflights Fare Finder

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. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Wed 9/7

11:24 a.m.-2:05 p.m.

2 stops25h 41m

Toronto Pearson Intl

Tue 15/7

6:30 a.m.-4:31 p.m.

1 stop11h 01m

C$ 413

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Mon 15/9

5:55 a.m.-5:49 p.m.

1 stop10h 54m

Toronto Pearson Intl

Wed 17/9

11:44 a.m.-9:53 p.m.

1 stop11h 09m

C$ 461

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Thu 18/9

7:23 a.m.-4:30 p.m.

1 stop8h 07m

Montreal Pierre Elliott Trudeau Intl

Tue 23/9

5:15 p.m.-9:26 a.m.

1 stop17h 11m

C$ 465

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sun 29/6

6:12 a.m.-4:50 p.m.

1 stop9h 38m

Toronto Pearson Intl

Thu 3/7

11:40 a.m.-11:30 a.m.

1 stop24h 50m

C$ 495

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sun 22/6

7:30 a.m.-10:25 a.m.

Nonstop1h 55m

Toronto Pearson Intl

Thu 26/6

11:30 a.m.-12:36 p.m.

Nonstop2h 06m

C$ 509

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 25/9

12:25 p.m.-9:02 p.m.

1 stop7h 37m

Toronto Pearson Intl

Sun 28/9

2:10 p.m.-2:27 p.m.

1 stop25h 17m

C$ 539

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Mon 14/7

10:47 a.m.-5:55 p.m.

2 stops30h 08m

Montreal Pierre Elliott Trudeau Intl

Mon 21/7

8:55 a.m.-4:31 p.m.

3 stops32h 36m

C$ 550

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Mon 11/8

6:45 p.m.-10:07 a.m.

1 stop14h 22m

Montreal Pierre Elliott Trudeau Intl

Mon 18/8

5:05 p.m.-8:06 a.m.

1 stop16h 01m

C$ 604

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 27/6

6:40 a.m.-2:41 p.m.

1 stop7h 01m

Toronto Pearson Intl

Tue 22/7

6:05 p.m.-8:36 p.m.

1 stop3h 31m

C$ 681

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Mon 11/8

5:30 p.m.-11:58 a.m.

1 stop17h 28m

Montreal Pierre Elliott Trudeau Intl

Tue 12/8

3:30 p.m.-9:59 a.m.

2 stops19h 29m

C$ 749

Flights are sorted by cheapest round-trip flights first.

Deals found on 11/6

Showing 1-10 of 28 results

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 C$ 167). Flying from St. Louis to Region of Ontario in July is currently the most expensive (average of C$ 255). 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?

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.

Weekly flight availability from St. Louis to Region of Ontario

The most flights from STL to CAON are scheduled on a Wednesday (4 on average). You will have fewer flight options on Sunday, which is when the least amount of flights are scheduled (2 on average).

Rainfall in Ontario by month

In terms of precipitation, rainfall in Region of Ontario ranges from 51.0 - 83.0 mm per month. June is typically the wettest month, when rainfall can reach 83.0 mm. February is typically the driest time to visit Region of Ontario when rainfall is around 51.0 mm.

Temperature in Ontario 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 21.0 C. Travellers hoping to avoid the cold should look outside of January, when temperatures are typically at their lowest (around -6.0 C).

Reviews of airlines servicing Ontario

Read through reviews of airlines operating flights from St. Louis to Ontario, such as Delta, United Airlines and American Airlines. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.

Delta

8.0

Very good

7,946 reviews

Check prices

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

7,946 reviews

Delta

8.0

Very good

7,946 reviews

Check prices

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

7,946 reviews

Check prices

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

7,946 reviews

Check prices

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

7,946 reviews

Check prices

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

9,537 reviews

Delta

8.0

Very good

7,946 reviews

Check prices

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

What airport do you fly from for flights from St. Louis to Ontario?
If you book a flight to Ontario from St. Louis, you will be flying from Lambert-St Louis, which is the city’s only airport. Lambert-St Louis (STL) is located 20.4 km from the centre of St. Louis.
What are the cheapest airlines to fly from St. Louis to Region of Ontario one-way?
For one-way options, check prices for American Airlines. According to our data, you can fly for as low as C$ 193. Users have also found prices from C$ 209 and C$ 246 on Sun Country Air and Delta, respectively.
What are the most popular routes from St. Louis to Region of Ontario?
The most popular flight routes from St. Louis to Region of Ontario are Lambert-St Louis - Toronto Pearson Intl, Lambert-St Louis - Montreal Pierre Elliott Trudeau Intl and Lambert-St Louis - London.
What are the most reliable airlines from St. Louis to Region of Ontario?
Before booking your flight to Region of Ontario from St. Louis, check out the most reliable airlines to get you to your destination on time: United Airlines (73%), Air Canada (50%), Jazz( 37%).
What are the cheapest flights from St. Louis to Region of Ontario?
The cheapest flight price from St. Louis to Region of Ontario is C$ 507. On average you can expect to pay C$ 586. The most popular route, (Lambert-St Louis - Toronto Pearson Intl), can usually be booked for C$ 427.
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 C$ 167). Flying from St. Louis to Region of Ontario in July is currently the most expensive (average of C$ 255). 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

Browse thousands of different options on Cheapflights for your next trip

Alternative routes for St. Louis to Ontario

Complete your trip

Region of Ontario car rentals

Toronto Pearson Intl Airport car rentals

Ottawa Airport car rentals

Toronto Island Airport car rentals

Hamilton Airport car rentals

Toronto Region of Waterloo Intl Airport car rentals

London Airport car rentals

Thunder Bay Airport car rentals

Sault Ste Marie Airport car rentals

Timmins Airport car rentals

Kingston Airport car rentals

North Bay Airport car rentals

Direct flights to Canada

Top airline flying from St. Louis to Ontario

Airline	Cheapest	Average	Flexibility	On-time
Air Canada	CheapestC$ 298	AverageC$ 772	FlexibilityNo cancel fee	On-time67%	Search Air Canada flights

Fly with Cheapflights

How does Cheapflights help users find flights from St. Louis to Ontario?

Cheapflights helps you search for flights from St. Louis to Ontario via 900+ travel sites so you don’t have to. After performing a flight search, users can also filter their flight selection by filtering for price, number of stops, airlines, and so on.

Why should you use Cheapflights to find cheap flight tickets from St. Louis to Ontario?

By finding flights from multiple airlines and providers at completely no cost, Cheapflights helps millions of users like you annually find the best flights to Ontario from St. Louis.

Can Cheapflights find flights from St. Louis to Ontario with no change fees?

Certainly. Search results for flights to Ontario from St. Louis shown to you on Cheapflights can be narrowed down with different useful search filters, which includes flexible booking options.

Can Cheapflights notify me if prices for flights from St. Louis to Ontario become cheaper?

Yes! Start tracking prices for St. Louis to Ontario flights today and get alerted whenever prices for these flights change. To access this feature, click the bell icon next to the flight deals above, which will prompt you for a valid email address to receive your alerts.

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Cheap flights from St. Louis to Ontario from C$ 193

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 25/9. Fares are subject to change and may not be available on all flights or dates of travel.

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 12 June 2025.

Round-trip from

One-way from

Popular in

Cheapest in

Average price

Good round-trip deal

Find flight deals from St. Louis to Ontario

Cheapest flights from St. Louis to OntarioExplore 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 12 June 2025.

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 12 June 2025.

Cheapflights Fare Finder

Use the filters below to find and compare flights from St. Louis to Ontario that are best for you.

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.

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?

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 12 June 2025.

Weekly flight availability from St. Louis to Region of Ontario

Explore weekly flight availability from St. Louis to Ontario. 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 12 June 2025.

Rainfall in Ontario by month

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

Temperature in Ontario by month

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

Reviews of airlines servicing Ontario

Read through reviews of airlines operating flights from St. Louis to Ontario, such as Delta, United Airlines and American Airlines. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.

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?

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

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

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

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

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

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

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

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

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Alternative routes for St. Louis to Ontario

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Top airline flying from St. Louis to Ontario

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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 12 June 2025.