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$ 189. Users have also found prices from C$ 258 and C$ 310 on Delta and United Airlines, respectively.

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.

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).

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$ 558. On average you can expect to pay C$ 754. The most popular route, (Lambert-St Louis - Toronto Pearson Intl), can usually be booked for C$ 490.

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 (80%), Air Canada (78%), Jazz( 75%).

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 367% 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$ 433. For sooner than that we have options available in the next 3 days from C$ 1,145.

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$ 589 per person but you can even find prices for as low as C$ 342. The most expensive prices can be found in the month of March. Opting for a January flight can save you 36% 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$ 189+ Flights from St. Louis to Ontario

Q: How much does it cost to fly round-trip from St. Louis to Region of Ontario?

Airfare is typical for this route at the moment. St. Louis to Region of Ontario flights typically cost between C$ 381 and C$ 712 in August. The cheapest round-trip price found within the last 3 days was C$ 457 on American Airlines (26 Aug-2 Sep).

Cheap flight deals from St. Louis to Ontario

Round-trip from	C$ 457
One-way from	C$ 189
Popular in	March
Cheapest in	January
Average price	C$ 675
Good round-trip deal	C$ 768 or less
Good one-way deal	C$ 611 or less

American Airlines
26/8-2/9
2 total stops
18h 38m total
St. Louis to Ontario

Search Deals

American Airlines
27/9
1 total stop
9h 20m 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 July 2025

Search Deals

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

Search Deals

Price to beat on a one-way 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 30 July 2025.

Tue 26/86:06 a.m.STL - YYZ

1 stop10h 35mAmerican Airlines

Tue 2/93:14 p.m.YYZ - STL

1 stop8h 03mAmerican Airlines

Deal found 27/7C$ 457

Wed 10/96:10 a.m.STL - YUL

1 stop9h 23mAmerican Airlines

Mon 15/95:15 p.m.YUL - STL

1 stop17h 11mAmerican Airlines

Deal found 30/7C$ 480

Thu 4/912:05 p.m.STL - YYZ

2 stops22h 30mMultiple Airlines

Sat 6/97:00 a.m.YYZ - STL

3 stops28h 50mMultiple Airlines

Deal found 29/7C$ 490

Thu 4/94:05 p.m.STL - YYZ

Nonstop1h 55mAir Canada

Sun 7/96:35 p.m.YYZ - STL

Nonstop2h 03mAir Canada

Deal found 29/7C$ 603

Tue 26/89:17 a.m.STL - YYZ

2 stops11h 57mUnited Airlines

Tue 2/98:15 a.m.YYZ - STL

1 stop8h 29mUnited Airlines

Deal found 27/7C$ 608

Thu 6/1112:20 p.m.STL - YUL

1 stop11h 25mMultiple Airlines

Sun 9/118:00 a.m.YUL - STL

3 stops29h 00mMultiple Airlines

Deal found 28/7C$ 629

Wed 10/91:30 p.m.STL - YUL

Nonstop2h 30mAir Canada

Wed 17/99:15 a.m.YUL - STL

1 stop7h 03mAir Canada

Deal found 29/7C$ 717

Tue 2/97:04 p.m.STL - YUL

2 stops20h 56mUnited Airlines

Sat 6/96:15 a.m.YUL - STL

1 stop10h 29mUnited Airlines

Deal found 28/7C$ 726

Wed 10/910:45 a.m.STL - YUL

2 stops10h 02mDelta

Wed 17/911:00 a.m.YUL - STL

1 stop10h 05mDelta

Deal found 29/7C$ 727

Fri 12/94:05 p.m.STL - YXU

1 stop4h 24mAir Canada

Fri 19/910:00 a.m.YXU - STL

1 stop6h 18mAir Canada

Deal found 29/7C$ 899

Sat 13/99:07 a.m.STL - YXU

2 stops29h 10mUnited Airlines

Sat 20/96:10 a.m.YXU - STL

2 stops15h 36mUnited Airlines

Deal found 30/7C$ 1,117

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 30 July 2025.

Tue 26/86:06 a.m.STL - YYZ

1 stop10h 35mAmerican Airlines

Tue 2/93:14 p.m.YYZ - STL

1 stop8h 03mAmerican Airlines

Deal found 27/7C$ 457

Thu 4/912:05 p.m.STL - YYZ

2 stops22h 30mMultiple Airlines

Sat 6/97:00 a.m.YYZ - STL

3 stops28h 50mMultiple Airlines

Deal found 29/7C$ 490

Thu 4/94:05 p.m.STL - YYZ

Nonstop1h 55mAir Canada

Sun 7/96:35 p.m.YYZ - STL

Nonstop2h 03mAir Canada

Deal found 29/7C$ 603

Tue 26/89:17 a.m.STL - YYZ

2 stops11h 57mUnited Airlines

Tue 2/98:15 a.m.YYZ - STL

1 stop8h 29mUnited Airlines

Deal found 27/7C$ 608

Wed 10/910:45 a.m.STL - YUL

2 stops10h 02mDelta

Wed 17/911:00 a.m.YUL - STL

1 stop10h 05mDelta

Deal found 29/7C$ 727

Wed 10/96:10 a.m.STL - YUL

1 stop9h 23mAmerican Airlines

Mon 15/95:15 p.m.YUL - STL

1 stop17h 11mAmerican Airlines

Deal found 30/7C$ 480

Thu 6/1112:20 p.m.STL - YUL

1 stop11h 25mMultiple Airlines

Sun 9/118:00 a.m.YUL - STL

3 stops29h 00mMultiple Airlines

Deal found 28/7C$ 629

Wed 10/91:30 p.m.STL - YUL

Nonstop2h 30mAir Canada

Wed 17/99:15 a.m.YUL - STL

1 stop7h 03mAir Canada

Deal found 29/7C$ 717

Tue 2/97:04 p.m.STL - YUL

2 stops20h 56mUnited Airlines

Sat 6/96:15 a.m.YUL - STL

1 stop10h 29mUnited Airlines

Deal found 28/7C$ 726

Fri 12/94:05 p.m.STL - YXU

1 stop4h 24mAir Canada

Fri 19/910:00 a.m.YXU - STL

1 stop6h 18mAir Canada

Deal found 29/7C$ 899

Sat 13/99:07 a.m.STL - YXU

2 stops29h 10mUnited Airlines

Sat 20/96:10 a.m.YXU - STL

2 stops15h 36mUnited Airlines

Deal found 30/7C$ 1,117

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 30 July 2025.

Thu 4/94:05 p.m.STL - YYZ

Nonstop1h 55mAir Canada

Sun 7/96:35 p.m.YYZ - STL

Nonstop2h 03mAir Canada

Deal found 29/7C$ 603

Mon 1/91:30 p.m.STL - YUL

Nonstop2h 30mAir Canada

Fri 5/96:10 p.m.YUL - STL

Nonstop2h 47mAir Canada

Deal found 29/7C$ 759

Tue 26/84:00 p.m.STL - YYZ

Nonstop2h 00mUnited Airlines

Tue 2/96:35 p.m.YYZ - STL

Nonstop2h 03mUnited Airlines

Deal found 29/7C$ 913

Thu 18/91:30 p.m.STL - YUL

Nonstop2h 30mUnited Airlines

Sun 21/96:10 p.m.YUL - STL

Nonstop2h 47mUnited Airlines

Deal found 28/7C$ 1,167

Tue 2/91:30 p.m.STL - YUL

Nonstop2h 30mMultiple Airlines

Fri 5/96:10 p.m.YUL - STL

Nonstop2h 47mMultiple Airlines

Deal found 29/7C$ 1,196

Mon 11/89:15 a.m.STL - YYZ

Nonstop2h 00mMultiple Airlines

Tue 12/86:35 p.m.YYZ - STL

Nonstop2h 10mMultiple Airlines

Deal found 29/7C$ 1,350

Last-minute flights from St. Louis to Ontario
Discover last-minute flight deals from St. Louis to Ontario. Data last updated 30 July 2025 and is based on user searches.

Tue 5/85:40 p.m.STL - YUL

2 stops18h 41mMultiple Airlines

Tue 12/82:30 p.m.YUL - STL

3 stops19h 41mMultiple Airlines

Deal found 29/7C$ 699

Tue 5/85:23 p.m.STL - YYZ

1 stop22h 52mWestJet

Wed 6/88:00 p.m.YYZ - STL

2 stops14h 41mWestJet

Deal found 28/7C$ 957

Wed 6/811:24 a.m.STL - YYZ

1 stop10h 20mMultiple Airlines

Mon 11/811:15 p.m.YYZ - STL

2 stops18h 16mMultiple Airlines

Deal found 30/7C$ 763

Wed 6/86:00 a.m.STL - YUL

1 stop14h 28mDelta

Wed 13/86:00 a.m.YUL - STL

1 stop9h 43mDelta

Deal found 29/7C$ 901

Wed 6/88:43 a.m.STL - YUL

2 stops7h 11mAmerican Airlines

Tue 12/810:34 a.m.YUL - STL

2 stops11h 28mAmerican Airlines

Deal found 29/7C$ 1,072

Sat 9/84:00 p.m.STL - YYZ

Nonstop2h 00mAir Canada

Tue 19/86:35 p.m.YYZ - STL

Nonstop2h 10mAir Canada

Deal found 27/7C$ 921

Sat 9/87:00 a.m.STL - YYZ

1 stop10h 31mAmerican Airlines

Mon 11/812:45 p.m.YYZ - STL

1 stop9h 19mAmerican Airlines

Deal found 29/7C$ 1,097

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

1 stop13h 45mDelta

Tue 19/87:55 a.m.YYZ - STL

1 stop14h 02mDelta

Deal found 27/7C$ 806

Wed 13/89:15 a.m.STL - YXU

1 stop4h 47mAir Canada

Sat 16/83:40 p.m.YXU - STL

1 stop5h 05mAir Canada

Deal found 30/7C$ 1,618

Thu 14/810:37 a.m.STL - YUL

2 stops12h 50mMultiple Airlines

Mon 18/86:00 a.m.YUL - STL

1 stop8h 32mMultiple Airlines

Deal found 27/7C$ 698

Thu 21/82:02 p.m.STL - YYZ

1 stop8h 45mMultiple Airlines

Mon 25/84:00 p.m.YYZ - STL

2 stops27h 41mMultiple Airlines

Deal found 28/7C$ 526

Thu 21/86:00 a.m.STL - YUL

1 stop9h 42mAmerican Airlines

Mon 25/812:30 p.m.YUL - STL

1 stop12h 21mAmerican Airlines

Deal found 28/7C$ 721

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 30 July 2025.

Sat 27/97:23 a.m.STL - YYZ

1 stop9h 20mAmerican Airlines

Deal found 28/7C$ 189

Sat 15/117:58 p.m.STL - YUL

1 stop18h 13mAmerican Airlines

Deal found 30/7C$ 197

Tue 14/1010:35 a.m.STL - YUL

1 stop27h 15mMultiple Airlines

Deal found 30/7C$ 211

Fri 12/99:50 a.m.STL - YYZ

3 stops27h 15mMultiple Airlines

Deal found 28/7C$ 212

Fri 12/96:05 a.m.STL - YYZ

1 stop16h 31mDelta

Deal found 29/7C$ 258

Tue 14/109:31 a.m.STL - YUL

1 stop8h 09mDelta

Deal found 28/7C$ 283

Sun 14/97:55 p.m.STL - YXU

2 stops32h 17mMultiple Airlines

Deal found 28/7C$ 294

Sat 23/88:10 a.m.STL - YYZ

2 stops13h 04mUnited Airlines

Deal found 28/7C$ 310

Sat 18/106:30 a.m.STL - YUL

2 stops12h 59mUnited Airlines

Deal found 28/7C$ 313

Wed 8/101:30 p.m.STL - YUL

Nonstop2h 30mAir Canada

Deal found 29/7C$ 314

Tue 26/89:15 a.m.STL - YYZ

Nonstop2h 00mAir Canada

Deal found 29/7C$ 316

Sun 14/99:15 a.m.STL - YXU

1 stop5h 02mAir Canada

Deal found 28/7C$ 550

Fly from

Fly to

Route

Depart

Return

Price

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Tue 26/8

6:06 a.m.-5:41 p.m.

1 stop10h 35m

Toronto Pearson Intl

Tue 2/9

3:14 p.m.-10:17 p.m.

1 stop8h 03m

C$ 457

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Wed 10/9

6:10 a.m.-4:33 p.m.

1 stop9h 23m

Montreal Pierre Elliott Trudeau Intl

Mon 15/9

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

1 stop17h 11m

C$ 480

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 4/9

12:05 p.m.-11:35 a.m.

2 stops22h 30m

Toronto Pearson Intl

Sat 6/9

7:00 a.m.-10:50 a.m.

3 stops28h 50m

C$ 490

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 4/9

4:05 p.m.-7:00 p.m.

Nonstop1h 55m

Toronto Pearson Intl

Sun 7/9

6:35 p.m.-7:38 p.m.

Nonstop2h 03m

C$ 603

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Tue 26/8

9:17 a.m.-10:14 p.m.

2 stops11h 57m

Toronto Pearson Intl

Tue 2/9

8:15 a.m.-3:44 p.m.

1 stop8h 29m

C$ 608

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Thu 6/11

12:20 p.m.-12:45 a.m.

1 stop11h 25m

Montreal Pierre Elliott Trudeau Intl

Sun 9/11

8:00 a.m.-12:00 p.m.

3 stops29h 00m

C$ 629

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Wed 10/9

1:30 p.m.-5:00 p.m.

Nonstop2h 30m

Montreal Pierre Elliott Trudeau Intl

Wed 17/9

9:15 a.m.-3:18 p.m.

1 stop7h 03m

C$ 717

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Tue 2/9

7:04 p.m.-5:00 p.m.

2 stops20h 56m

Montreal Pierre Elliott Trudeau Intl

Sat 6/9

6:15 a.m.-3:44 p.m.

1 stop10h 29m

C$ 726

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Wed 10/9

10:45 a.m.-9:47 p.m.

2 stops10h 02m

Montreal Pierre Elliott Trudeau Intl

Wed 17/9

11:00 a.m.-8:05 p.m.

1 stop10h 05m

C$ 727

St. LouisLondon

STL - YXU

STLYXU

Lambert-St Louis

Fri 12/9

4:05 p.m.-9:29 p.m.

1 stop4h 24m

London

Fri 19/9

10:00 a.m.-3:18 p.m.

1 stop6h 18m

C$ 899

Flights are sorted by cheapest round-trip flights first.

Deals found on 28/7

Showing 1-10 of 23 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$ 258). 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 Monday (4 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (4 on average).

How much does it cost to fly round-trip from St. Louis to Region of Ontario?

Reviews of airlines servicing Ontario

See what other customers who have flown with Delta,United Airlines, andAmerican Airlines from St. Louis to Ontario have to say. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.

Delta

8.0

Very good

7,980 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

7,980 reviews

Delta

8.0

Very good

7,980 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

8,896 reviews

Delta

8.0

Very good

7,980 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

7,980 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

9,837 reviews

Delta

8.0

Very good

7,980 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$ 189. Users have also found prices from C$ 258 and C$ 310 on Delta and United Airlines, 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 (80%), Air Canada (78%), Jazz( 75%).
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$ 558. On average you can expect to pay C$ 754. The most popular route, (Lambert-St Louis - Toronto Pearson Intl), can usually be booked for C$ 490.
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$ 258). 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

London Airport car rentals

Toronto Region of Waterloo Intl Airport car rentals

Thunder Bay Airport car rentals

Sault Ste Marie Airport car rentals

Kingston Airport car rentals

Timmins 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$ 301	AverageC$ 690	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.

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.

Cheap flights from St. Louis to Ontario from C$ 189

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 27/9. 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 30 July 2025.

Round-trip from

One-way from

Popular in

Cheapest in

Average price

Good round-trip deal

Good one-way 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 30 July 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 30 July 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 30 July 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 30 July 2025.

How much does it cost to fly round-trip from St. Louis to Region of Ontario?

Reviews of airlines servicing Ontario

See what other customers who have flown with Delta,United Airlines, andAmerican Airlines from St. Louis to Ontario have to say. Users can see the overall rating for each airline as well as how each is rated in terms of 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?

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for St. Louis to Ontario

See prices for flight routes from nearby airports that may be better suited for you.

Top airline flying from St. Louis to Ontario

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travelers can enjoy low prices and a wide availability of flights to their desired destinations.

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

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

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

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

100% Free

Book with Flexibility

Travel Smart

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 30 July 2025.