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$ 270. Users have also found prices from C$ 280 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 cheapest flights from St. Louis to Region of Ontario?

The cheapest flight price from St. Louis to Region of Ontario is C$ 198. On average you can expect to pay C$ 466. The most popular route, (Lambert-St Louis - Toronto Pearson Intl), can usually be booked for C$ 456.

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: Air Canada (71%), Jazz (71%), United Airlines( 71%).

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$ 482. For sooner than that we have options available in the next 3 days from C$ 1,299.

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

May is one of the best times of the year to fly to Region of Ontario from St. Louis. Prices for May average C$ 567 per person but you can even find prices for as low as C$ 326. The most expensive prices can be found in the month of March. Opting for a May flight can save you 46% 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$ 173+ Flights from St. Louis to Ontario

Cheap flight deals from St. Louis to Ontario

Round-trip from	C$ 466
One-way from	C$ 173
Popular in	March
Cheapest in	May
Average price	C$ 833
Good round-trip deal	C$ 312 or less
Good one-way deal	C$ 238 or less

26/4-11/5
3 total stops
42h 55m total
St. Louis to Ontario

Search Deals

8/4
1 total stop
17h 48m total
St. Louis to Ontario

Search Deals

Highest demand for flights based on searches. 5% potential increase in price (C$ 45 potential increase over avg. RT price).

Search Deals

Cheapest flight prices on average. 4% potential price decrease (C$ 36 potential savings vs. average RT price).

Search Deals

Average for round-trip flights in March 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 28 March 2025.

Fri 4/44:57 p.m.STL - YYZ

1 stop19h 58mMultiple Airlines

Tue 8/48:15 p.m.YYZ - STL

1 stop28h 31mMultiple Airlines

Deal found 27/3C$ 459

Thu 17/44:57 p.m.STL - YUL

1 stop20h 13mMultiple Airlines

Sun 20/47:15 a.m.YUL - STL

1 stop11h 00mMultiple Airlines

Deal found 27/3C$ 513

Thu 8/56:00 a.m.STL - YYZ

1 stop9h 10mDelta

Mon 12/510:20 a.m.YYZ - STL

1 stop8h 42mDelta

Deal found 27/3C$ 559

Thu 1/57:30 a.m.STL - YYZ

Nonstop1h 55mAir Canada

Sun 4/511:30 a.m.YYZ - STL

Nonstop2h 06mAir Canada

Deal found 27/3C$ 602

Tue 6/56:00 a.m.STL - YYZ

1 stop7h 30mAmerican Airlines

Wed 7/511:32 a.m.YYZ - STL

1 stop11h 20mAmerican Airlines

Deal found 27/3C$ 620

Fri 18/46:00 p.m.STL - YUL

1 stop16h 44mAmerican Airlines

Mon 21/412:30 p.m.YUL - STL

1 stop12h 03mAmerican Airlines

Deal found 27/3C$ 646

Tue 22/45:35 p.m.STL - YYZ

1 stop21h 11mUnited Airlines

Thu 24/47:00 a.m.YYZ - STL

1 stop8h 42mUnited Airlines

Deal found 27/3C$ 696

Thu 24/49:39 a.m.STL - YUL

1 stop8h 12mUnited Airlines

Thu 1/56:15 a.m.YUL - STL

1 stop10h 32mUnited Airlines

Deal found 27/3C$ 728

Sun 20/46:50 a.m.STL - YYZ

1 stop3h 35mWestJet

Thu 24/41:27 p.m.YYZ - STL

1 stop5h 29mWestJet

Deal found 28/3C$ 742

Sun 15/65:00 a.m.STL - YUL

1 stop7h 55mAir Canada

Sat 21/66:10 p.m.YUL - STL

Nonstop2h 48mAir Canada

Deal found 28/3C$ 845

Thu 10/76:00 a.m.STL - YUL

1 stop9h 05mDelta

Tue 15/76:00 a.m.YUL - STL

1 stop9h 49mDelta

Deal found 28/3C$ 869

Mon 13/105:30 p.m.STL - YUL

1 stop4h 48mWestJet

Sat 18/1012:45 p.m.YUL - STL

1 stop5h 02mWestJet

Deal found 27/3C$ 1,013

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 28 March 2025.

Sat 26/45:41 p.m.STL - YYZ

1 stop15h 14mMultiple Airlines

Sun 11/54:00 p.m.YYZ - STL

2 stops27h 41mMultiple Airlines

Deal found 27/3C$ 466

Thu 8/56:00 a.m.STL - YYZ

1 stop9h 10mDelta

Mon 12/510:20 a.m.YYZ - STL

1 stop8h 42mDelta

Deal found 27/3C$ 559

Thu 1/57:30 a.m.STL - YYZ

Nonstop1h 55mAir Canada

Sun 4/511:30 a.m.YYZ - STL

Nonstop2h 06mAir Canada

Deal found 27/3C$ 602

Tue 6/56:00 a.m.STL - YYZ

1 stop7h 30mAmerican Airlines

Wed 7/511:32 a.m.YYZ - STL

1 stop11h 20mAmerican Airlines

Deal found 27/3C$ 620

Tue 22/45:35 p.m.STL - YYZ

1 stop21h 11mUnited Airlines

Thu 24/47:00 a.m.YYZ - STL

1 stop8h 42mUnited Airlines

Deal found 27/3C$ 696

Sun 20/46:50 a.m.STL - YYZ

1 stop3h 35mWestJet

Thu 24/41:27 p.m.YYZ - STL

1 stop5h 29mWestJet

Deal found 28/3C$ 742

Thu 17/44:57 p.m.STL - YUL

1 stop20h 13mMultiple Airlines

Sun 20/47:15 a.m.YUL - STL

1 stop11h 00mMultiple Airlines

Deal found 27/3C$ 513

Sat 19/46:44 a.m.STL - YYZ

1 stop31h 16mAlaska Airlines

Fri 25/44:45 p.m.YYZ - STL

2 stops30h 43mAlaska Airlines

Deal found 27/3C$ 1,109

Fri 18/46:00 p.m.STL - YUL

1 stop16h 44mAmerican Airlines

Mon 21/412:30 p.m.YUL - STL

1 stop12h 03mAmerican Airlines

Deal found 27/3C$ 646

Thu 24/49:39 a.m.STL - YUL

1 stop8h 12mUnited Airlines

Thu 1/56:15 a.m.YUL - STL

1 stop10h 32mUnited Airlines

Deal found 27/3C$ 728

Sun 15/65:00 a.m.STL - YUL

1 stop7h 55mAir Canada

Sat 21/66:10 p.m.YUL - STL

Nonstop2h 48mAir Canada

Deal found 28/3C$ 845

Thu 10/76:00 a.m.STL - YUL

1 stop9h 05mDelta

Tue 15/76:00 a.m.YUL - STL

1 stop9h 49mDelta

Deal found 28/3C$ 869

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 28 March 2025.

Thu 1/57:30 a.m.STL - YYZ

Nonstop1h 55mAir Canada

Sun 4/511:30 a.m.YYZ - STL

Nonstop2h 06mAir Canada

Deal found 27/3C$ 602

Tue 6/52:30 p.m.STL - YYZ

Nonstop2h 00mMultiple Airlines

Wed 7/511:30 a.m.YYZ - STL

Nonstop2h 06mMultiple Airlines

Deal found 27/3C$ 730

Sun 11/57:30 a.m.STL - YYZ

Nonstop1h 55mUnited Airlines

Sun 18/511:30 a.m.YYZ - STL

Nonstop2h 06mUnited Airlines

Deal found 27/3C$ 763

Fri 2/51:30 p.m.STL - YUL

Nonstop2h 29mUnited Airlines

Fri 9/56:10 p.m.YUL - STL

Nonstop2h 48mUnited Airlines

Deal found 27/3C$ 832

Mon 9/61:30 p.m.STL - YUL

Nonstop2h 30mAir Canada

Fri 13/66:10 p.m.YUL - STL

Nonstop2h 48mAir Canada

Deal found 27/3C$ 929

Last-minute flights from St. Louis to Ontario
Discover last-minute flight deals from St. Louis to Ontario. Data last updated 28 March 2025 and is based on user searches.

Wed 2/48:25 a.m.STL - YYZ

2 stops13h 02mUnited Airlines

Fri 4/46:15 a.m.YYZ - STL

2 stops10h 32mUnited Airlines

Deal found 26/3C$ 1,294

Thu 3/43:30 p.m.STL - YYZ

Nonstop2h 00mAir Canada

Tue 8/41:40 p.m.YYZ - STL

Nonstop2h 09mAir Canada

Deal found 27/3C$ 1,466

Fri 4/44:57 p.m.STL - YYZ

1 stop19h 58mMultiple Airlines

Tue 8/48:15 p.m.YYZ - STL

1 stop28h 31mMultiple Airlines

Deal found 27/3C$ 459

Fri 4/46:10 a.m.STL - YUL

1 stop9h 20mDelta

Sun 6/46:00 a.m.YUL - STL

1 stop9h 46mDelta

Deal found 27/3C$ 1,075

Fri 4/47:33 a.m.STL - YUL

1 stop8h 12mAmerican Airlines

Sun 6/410:39 a.m.YUL - STL

2 stops9h 44mAmerican Airlines

Deal found 27/3C$ 1,213

Thu 17/44:57 p.m.STL - YUL

1 stop20h 13mMultiple Airlines

Sun 20/47:15 a.m.YUL - STL

1 stop11h 00mMultiple Airlines

Deal found 27/3C$ 513

Fri 18/46:00 p.m.STL - YUL

1 stop16h 44mAmerican Airlines

Mon 21/412:30 p.m.YUL - STL

1 stop12h 03mAmerican Airlines

Deal found 27/3C$ 646

Sat 19/46:44 a.m.STL - YYZ

1 stop31h 16mAlaska Airlines

Fri 25/44:45 p.m.YYZ - STL

2 stops30h 43mAlaska Airlines

Deal found 27/3C$ 1,109

Sun 20/46:13 a.m.STL - YYZ

1 stop9h 22mAmerican Airlines

Thu 24/43:14 p.m.YYZ - STL

1 stop9h 19mAmerican Airlines

Deal found 27/3C$ 679

Sun 20/46:50 a.m.STL - YYZ

1 stop3h 35mWestJet

Thu 24/41:27 p.m.YYZ - STL

1 stop5h 29mWestJet

Deal found 28/3C$ 742

Mon 21/46:50 a.m.STL - YYZ

1 stop7h 19mDelta

Thu 24/410:20 a.m.YYZ - STL

1 stop8h 58mDelta

Deal found 28/3C$ 748

Tue 22/45:35 p.m.STL - YYZ

1 stop21h 11mUnited Airlines

Thu 24/47:00 a.m.YYZ - STL

1 stop8h 42mUnited Airlines

Deal found 27/3C$ 696

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 28 March 2025.

Tue 8/44:57 p.m.STL - YYZ

1 stop17h 48mMultiple Airlines

Deal found 27/3C$ 173

Sat 19/46:13 a.m.STL - YYZ

1 stop9h 22mAmerican Airlines

Deal found 27/3C$ 270

Sat 26/73:40 p.m.STL - YYZ

1 stop16h 36mDelta

Deal found 27/3C$ 280

Wed 23/46:30 a.m.STL - YYZ

1 stop8h 16mUnited Airlines

Deal found 27/3C$ 310

Tue 22/79:15 a.m.STL - YYZ

Nonstop1h 58mAir Canada

Deal found 27/3C$ 314

Fri 25/45:35 p.m.STL - YUL

2 stops18h 34mUnited Airlines

Deal found 27/3C$ 360

Thu 4/912:00 p.m.STL - YUL

1 stop8h 30mDelta

Deal found 28/3C$ 362

Fri 25/45:00 p.m.STL - YUL

1 stop15h 50mAmerican Airlines

Deal found 27/3C$ 369

Sun 20/411:15 a.m.STL - YYZ

1 stop11h 00mWestJet

Deal found 27/3C$ 382

Thu 4/91:30 p.m.STL - YUL

Nonstop2h 30mAir Canada

Deal found 28/3C$ 479

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

Sat 26/4

5:41 p.m.-9:55 a.m.

1 stop15h 14m

Toronto Pearson Intl

Sun 11/5

4:00 p.m.-6:41 p.m.

2 stops27h 41m

C$ 466

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Thu 17/4

4:57 p.m.-2:10 p.m.

1 stop20h 13m

Montreal Pierre Elliott Trudeau Intl

Sun 20/4

7:15 a.m.-5:15 p.m.

1 stop11h 00m

C$ 513

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 8/5

6:00 a.m.-4:10 p.m.

1 stop9h 10m

Toronto Pearson Intl

Mon 12/5

10:20 a.m.-6:02 p.m.

1 stop8h 42m

C$ 559

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 1/5

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

Nonstop1h 55m

Toronto Pearson Intl

Sun 4/5

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

Nonstop2h 06m

C$ 602

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Tue 6/5

6:00 a.m.-2:30 p.m.

1 stop7h 30m

Toronto Pearson Intl

Wed 7/5

11:32 a.m.-9:52 p.m.

1 stop11h 20m

C$ 620

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Fri 18/4

6:00 p.m.-11:44 a.m.

1 stop16h 44m

Montreal Pierre Elliott Trudeau Intl

Mon 21/4

12:30 p.m.-11:33 p.m.

1 stop12h 03m

C$ 646

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Tue 22/4

5:35 p.m.-3:46 p.m.

1 stop21h 11m

Toronto Pearson Intl

Thu 24/4

7:00 a.m.-2:42 p.m.

1 stop8h 42m

C$ 696

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Thu 24/4

9:39 a.m.-6:51 p.m.

1 stop8h 12m

Montreal Pierre Elliott Trudeau Intl

Thu 1/5

6:15 a.m.-3:47 p.m.

1 stop10h 32m

C$ 728

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sun 20/4

6:50 a.m.-11:25 a.m.

1 stop3h 35m

Toronto Pearson Intl

Thu 24/4

1:27 p.m.-5:56 p.m.

1 stop5h 29m

C$ 742

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Sun 15/6

5:00 a.m.-1:55 p.m.

1 stop7h 55m

Montreal Pierre Elliott Trudeau Intl

Sat 21/6

6:10 p.m.-7:58 p.m.

Nonstop2h 48m

C$ 845

Flights are sorted by cheapest round-trip flights first.

Deals found on 27/3

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.

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 Alaska Airlines, Delta and United Airlines. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.

Alaska Airlines

8.0

Very good

9,798 reviews

Check prices

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

9,798 reviews

Alaska Airlines

8.0

Very good

9,798 reviews

Check prices

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

7,896 reviews

Alaska Airlines

8.0

Very good

9,798 reviews

Check prices

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

8,603 reviews

Alaska Airlines

8.0

Very good

9,798 reviews

Check prices

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

9,798 reviews

Check prices

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

2,785 reviews

Alaska Airlines

8.0

Very good

9,798 reviews

Check prices

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

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$ 270. Users have also found prices from C$ 280 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: Air Canada (71%), Jazz (71%), United Airlines( 71%).
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$ 198. On average you can expect to pay C$ 466. The most popular route, (Lambert-St Louis - Toronto Pearson Intl), can usually be booked for C$ 456.
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

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$ 312	AverageC$ 802	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$ 173

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 8/4. 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 28 March 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 28 March 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 28 March 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 28 March 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 Alaska Airlines, Delta and United 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 28 March 2025.