What are the cheapest airlines flying from Ontario to St. Louis round-trip?

Flying on Frontier is currently your cheapest option to St. Louis, with prices starting at $108. Additional round-trip tickets that might be worth considering are offered by Delta and American Airlines, with the lowest prices starting at $306 and $311, respectively. Frontier is priced at 67% lower than the current average price of a flight leaving 3 months from now.

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

The cheapest airlines for a one-way flight from Ontario to St. Louis are Frontier ($53), Delta ($158), and Alaska Airlines ($163).

What are the most popular airlines that fly from Ontario to St. Louis?

Before booking your flight from Ontario to St. Louis check out the most popular airlines for this route: American Airlines, Delta or Frontier.

What is the cheapest day to fly round-trip from Ontario to St. Louis?

Leaving on a Monday is a viable option for saving on travel. Heavily demanded days of the week can typically drive up the prices you see. Booking your travel for a less competitive day can save up to 54% on the overall cost on flights from Ontario to St. Louis.

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

Users have found that booking a flight from Ontario to St. Louis at least 48 days early can save you up to 68% on average compared to booking a flight this week. If booking 48 days before your flight isn’t an option for you, users have found flights from Ontario to St. Louis for as little as $420 when booking for a departure date within the next two weeks. You can also check prices now. Some users have found airline tickets as low as $595 for flights departing within the next 3 days.

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

The best pricing can be found in the month of August. Prices to St. Louis from Ontario average $390. You can even find prices in August for less than $390, as users have found deals to St. Louis from as low as $170. The month of December appears to be one of the more expensive times to travel to St. Louis from Ontario. Flying in the targeted month can save you up to 15%.

Most accurate provider : When it comes to deals on Ontario-St. Louis flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Ontario-St. Louis flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Ontario-St. Louis flight searches over the past month and is updated monthly.

Most trusted provider : When it comes to deals on Ontario-St. Louis flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Ontario-St. Louis flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

What airports do I use to fly from Ontario to St. Louis?

If you book a flight from Ontario to St. Louis, you will be flying from Ontario to Lambert-St Louis. Flights to Lambert-St Louis (STL) from Ontario (ONT) take 5h 28m for a nonstop flight. There is 1 flight from Ontario to St. Louis per day from 5 airlines.

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.

$53+ Flights from Ontario, California to St. Louis, Missouri

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1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

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3. Compare prices and book

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The best prices from Ontario to Lambert-St Louis are usually found in June or September, booked 53 days in advance, depart on a Tuesday or Wednesday and return on a Tuesday

Cheap flight deals from Ontario to St. Louis

Most accurate provider	FlightHub 3 stars
Most trusted provider	FlightHub 3 stars
Popular in	December
Cheapest in	June
Round-trip from	$108 (Frontier)
One-way from	$53 (Cheapflightsfares)

Provider with most accurate pricing for Ontario-Lambert-St Louis flight deals.

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Provider most trusted by Cheapflights users for Ontario-Lambert-St Louis flights.

Search Deals

High demand for flights, 41% potential price rise

Search Deals

Best time to find cheap flights, 28% potential price drop

Search Deals

From Ontario to Lambert-St Louis

Search Deals

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 noviembre 20, 2024.

jue. 12/58:04 amONT - STL

1 stop9h 30mFrontier

sáb. 12/76:46 pmSTL - ONT

1 stop6h 58mFrontier

Deal found 11/19

$108

mié. 12/116:10 amONT - STL

1 stop5h 22mAmerican Airlines

sáb. 12/147:20 amSTL - ONT

1 stop6h 40mAmerican Airlines

Deal found 11/19

$306

mié. 12/1111:18 amONT - STL

2 stops11h 39mDelta

dom. 12/157:20 amSTL - ONT

1 stop7h 05mDelta

Deal found 11/18

$335

mar. 12/315:05 amONT - STL

1 stop5h 43mUnited Airlines

mar. 1/74:36 pmSTL - ONT

1 stop7h 21mUnited Airlines

Deal found 11/19

$396

mié. 12/116:45 amONT - STL

2 stops8h 20mSouthwest

dom. 12/1511:45 amSTL - ONT

2 stops7h 50mSouthwest

Deal found 11/18

$407

vie. 12/67:44 pmONT - STL

2 stops15h 40mAlaska Airlines

mié. 12/117:00 amSTL - ONT

1 stop7h 58mAlaska Airlines

Deal found 11/18

$462

mar. 11/196:00 amONT - STL

2 stops15h 56mMultiple Airlines

sáb. 11/2310:17 pmSTL - ONT

1 stop10h 51mMultiple Airlines

Deal found 11/18

$733

Best flights from Ontario to St. Louis
Discover carefully curated flight deals from Ontario to St. Louis that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated noviembre 20, 2024.

jue. 12/58:04 amONT - STL

1 stop9h 30mFrontier

mié. 12/116:46 pmSTL - ONT

1 stop6h 58mFrontier

Deal found 11/18

$108

vie. 1/2411:14 amONT - STL

2 stops10h 45mMultiple Airlines

dom. 1/268:31 pmSTL - ONT

1 stop12h 40mMultiple Airlines

Deal found 11/19

$276

sáb. 1/187:00 amONT - STL

1 stop6h 30mDelta

mar. 1/217:40 amSTL - ONT

1 stop6h 46mDelta

Deal found 11/20

$306

sáb. 1/1810:56 amONT - STL

1 stop5h 27mAmerican Airlines

mar. 1/2111:38 amSTL - ONT

2 stops8h 46mAmerican Airlines

Deal found 11/19

$311

mar. 12/315:05 amONT - STL

1 stop5h 43mUnited Airlines

mar. 1/74:36 pmSTL - ONT

1 stop7h 21mUnited Airlines

Deal found 11/19

$396

sáb. 2/155:44 pmONT - STL

2 stops18h 41mAlaska Airlines

lun. 2/177:00 amSTL - ONT

1 stop30h 02mAlaska Airlines

Deal found 11/19

$402

mié. 12/116:45 amONT - STL

2 stops8h 20mSouthwest

dom. 12/1511:45 amSTL - ONT

2 stops7h 50mSouthwest

Deal found 11/18

$407

Last-minute flights from Ontario to St. Louis
Discover last-minute flight deals from Ontario to St. Louis. Data last updated noviembre 20, 2024 and is based on user searches.

lun. 11/255:05 amONT - STL

1 stop5h 38mUnited Airlines

mar. 12/34:45 pmSTL - ONT

1 stop6h 57mUnited Airlines

Deal found 11/18

$522

lun. 11/252:22 pmONT - STL

1 stop7h 37mAlaska Airlines

mar. 12/37:15 amSTL - ONT

2 stops14h 45mAlaska Airlines

Deal found 11/18

$797

mar. 11/265:00 pmONT - STL

1 stop5h 42mDelta

mar. 12/35:05 pmSTL - ONT

1 stop7h 56mDelta

Deal found 11/19

$477

vie. 11/296:30 amONT - STL

1 stop10h 21mFrontier

mié. 12/46:46 pmSTL - ONT

1 stop6h 58mFrontier

Deal found 11/19

$239

jue. 12/58:04 amONT - STL

1 stop9h 30mFrontier

sáb. 12/76:46 pmSTL - ONT

1 stop6h 58mFrontier

Deal found 11/19

$108

vie. 12/67:44 pmONT - STL

2 stops15h 40mAlaska Airlines

mié. 12/117:00 amSTL - ONT

1 stop7h 58mAlaska Airlines

Deal found 11/18

$462

mié. 12/116:10 amONT - STL

1 stop5h 22mAmerican Airlines

sáb. 12/147:20 amSTL - ONT

1 stop6h 40mAmerican Airlines

Deal found 11/19

$306

mié. 12/1111:18 amONT - STL

2 stops11h 39mDelta

dom. 12/157:20 amSTL - ONT

1 stop7h 05mDelta

Deal found 11/18

$335

mié. 12/116:45 amONT - STL

2 stops8h 20mSouthwest

dom. 12/1511:45 amSTL - ONT

2 stops7h 50mSouthwest

Deal found 11/18

$407

mar. 12/315:05 amONT - STL

1 stop5h 43mUnited Airlines

mar. 1/74:36 pmSTL - ONT

1 stop7h 21mUnited Airlines

Deal found 11/19

$396

One-way flights from Ontario to St. Louis
Search for one-way flight options from Ontario to St. Louis. Find affordable one-way fares based on user searches. Data last updated noviembre 20, 2024.

lun. 1/61:05 pmONT - STL

1 stop5h 24mFrontier

Deal found 11/19

$53

mar. 12/105:10 pmONT - STL

1 stop5h 47mDelta

Deal found 11/18

$158

mar. 2/411:14 amONT - STL

2 stops24h 39mAlaska Airlines

Deal found 11/20

$163

mar. 2/186:00 amONT - STL

1 stop7h 11mUnited Airlines

Deal found 11/20

$198

vie. 12/206:20 amONT - STL

2 stops6h 30mSouthwest

Deal found 11/19

$243

mié. 12/46:10 amONT - STL

2 stops11h 18mAmerican Airlines

Deal found 11/19

$263

lun. 2/178:56 pmONT - STL

3 stops19h 31mMultiple Airlines

Deal found 11/19

$519

Find flights from Ontario to St. Louis within your budget

Fly from

Fly to

Route

Depart

Return

Price

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

jue. 12/5

8:04 am-7:34 pm

1 stop9h 30m

Lambert-St Louis

mié. 12/11

6:46 pm-11:44 pm

1 stop6h 58m

$108

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

vie. 1/24

11:14 am-11:59 pm

2 stops10h 45m

Lambert-St Louis

dom. 1/26

8:31 pm-7:11 am

1 stop12h 40m

$276

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

sáb. 1/18

7:00 am-3:30 pm

1 stop6h 30m

Lambert-St Louis

mar. 1/21

7:40 am-12:26 pm

1 stop6h 46m

$306

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

sáb. 1/18

10:56 am-6:23 pm

1 stop5h 27m

Lambert-St Louis

mar. 1/21

11:38 am-6:24 pm

2 stops8h 46m

$311

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

mar. 12/31

5:05 am-12:48 pm

1 stop5h 43m

Lambert-St Louis

mar. 1/7

4:36 pm-9:57 pm

1 stop7h 21m

$396

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

sáb. 2/15

5:44 pm-2:25 pm

2 stops18h 41m

Lambert-St Louis

lun. 2/17

7:00 am-11:02 am

1 stop30h 02m

$402

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

mié. 12/11

6:45 am-5:05 pm

2 stops8h 20m

Lambert-St Louis

dom. 12/15

11:45 am-5:35 pm

2 stops7h 50m

$407

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

lun. 1/6

1:05 pm-8:29 pm

1 stop5h 24m

$53

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

mar. 12/10

5:10 pm-12:57 am

1 stop5h 47m

$158

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

mar. 2/4

11:14 am-1:53 pm

2 stops24h 39m

$163

Flights are sorted by cheapest round-trip flights first.

Deals found on 11/19

Showing 1-10 of 14 results

Compare providers for flights from Ontario to St. Louis

Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Ontario to St. Louis in November.

Provider	Price Accuracy	Trust Score*
Expedia	Price Accuracy1 star	Trust Score*3 stars
FlightHub	Price Accuracy3 stars	Trust Score*3 stars
eDreams	Price Accuracy3 stars	Trust Score*3 stars
Priceline	Price Accuracy1 star	Trust Score*3 stars
Mytrip	Price Accuracy3 stars	Trust Score*3 stars

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

Most accurate provider: When it comes to deals on Ontario-St. Louis flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Ontario-St. Louis flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Ontario-St. Louis flight searches over the past month and is updated monthly.
Most trusted provider: When it comes to deals on Ontario-St. Louis flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Ontario-St. Louis flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

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.

Travel insights for flights from Ontario to St. Louis

Get recent, data-driven insights about flights from Ontario to St. Louis including ideal travel times, pricing trends, and more.

How far ahead should I book a flight from Ontario to St. Louis?

The best time to book flights from Ontario to St. Louis is 53 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.

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

Currently, September is the cheapest month in which you can book a flight from Ontario to St. Louis (average of $308). Flying from Ontario to St. Louis in March is currently the most expensive (average of $357). 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 ONT to STL?

A simple way to save on the total cost of your ticket is to fly from Ontario to St. Louis in the evening. If you’re flexible enough to do this you can expect to save up to 48% on your trip compared to booking a flight in the afternoon.

What is the cheapest day to fly from Ontario to St. Louis?

Travelers seeking maximum savings on their Ontario to St. Louis flight should consider departing on Wednesday at noon when fares are most often at their lowest. Sunday at noon flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from Ontario to St. Louis

The most flights from ONT to STL are scheduled on a Monday (2 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (1 on average).

Rainfall in St. Louis 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

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

Read through reviews of airlines operating flights from Ontario to St. Louis, such as Frontier, Delta and United Airlines. In addition to providing an overall rating, users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.

Southwest

8.1

Very good

5,014 reviews

Reviews

1 / 10

My original flight was delayed so they found this flight for me so I could arrive at a reasonable time

Southwest

8.1

Very good

5,014 reviews

Southwest

8.1

Very good

5,014 reviews

Reviews

1 / 10

My original flight was delayed so they found this flight for me so I could arrive at a reasonable time

Alaska Airlines

8.0

Very good

9,461 reviews

Southwest

8.1

Very good

5,014 reviews

Reviews

1 / 10

My original flight was delayed so they found this flight for me so I could arrive at a reasonable time

Delta

8.0

Very good

8,756 reviews

Southwest

8.1

Very good

5,014 reviews

Reviews

1 / 10

My original flight was delayed so they found this flight for me so I could arrive at a reasonable time

United Airlines

7.4

Good

9,171 reviews

Southwest

8.1

Very good

5,014 reviews

Reviews

1 / 10

My original flight was delayed so they found this flight for me so I could arrive at a reasonable time

American Airlines

7.2

Good

10,000 reviews

Southwest

8.1

Very good

5,014 reviews

Reviews

1 / 10

My original flight was delayed so they found this flight for me so I could arrive at a reasonable time

Related info for your journey

What airports do I use to fly from Ontario to St. Louis?
If you book a flight from Ontario to St. Louis, you will be flying from Ontario to Lambert-St Louis. Flights to Lambert-St Louis (STL) from Ontario (ONT) take 5h 28m for a nonstop flight. There is 1 flight from Ontario to St. Louis per day from 5 airlines.
What are the cheapest airlines flying from Ontario to St. Louis round-trip?
Flying on Frontier is currently your cheapest option to St. Louis, with prices starting at $108. Additional round-trip tickets that might be worth considering are offered by Delta and American Airlines, with the lowest prices starting at $306 and $311, respectively. Frontier is priced at 67% lower than the current average price of a flight leaving 3 months from now.
What are the cheapest airlines to fly from Ontario to St. Louis one-way?
The cheapest airlines for a one-way flight from Ontario to St. Louis are Frontier ($53), Delta ($158), and Alaska Airlines ($163).
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 Ontario to St. Louis?
Currently, September is the cheapest month in which you can book a flight from Ontario to St. Louis (average of $308). Flying from Ontario to St. Louis in March is currently the most expensive (average of $357). 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

Top 5 airlines flying from Ontario to St. Louis

Airline	Cheapest	Average	Flexibility	On-time
Frontier	Cheapest$105	Average$186	FlexibilityNo cancel fee	On-time62%
Delta	Cheapest$276	Average$401	FlexibilityNo cancel fee	On-timeN/A
American Airlines	Cheapest$282	Average$439	FlexibilityNo cancel fee	On-time71%
United Airlines	Cheapest$288	Average$481	FlexibilityNo cancel fee	On-time69%
Southwest	Cheapest$326	Average$381	FlexibilityNo cancel fee	On-time63%

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$53+ Cheap flights from Ontario to St. Louis (ONT - 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 1/6. Fares are subject to change and may not be available on all flights or dates of travel.

Find cheap flights from Ontario to St. Louis with Cheapflights

1. Tell us where you want to go

2. Select your favorite providers

3. Compare prices and book

The best prices from Ontario to Lambert-St Louis are usually found in June or September, booked 53 days in advance, depart on a Tuesday or Wednesday and return on a Tuesday

Cheap flight deals from Ontario to St. Louis

Most accurate provider

Most trusted provider

Popular in

Cheapest in

Round-trip from

One-way from

Find flight deals from Ontario to St. Louis

Cheapest flights from Ontario to St. LouisExplore 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 noviembre 20, 2024.

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 noviembre 20, 2024.

Find flights from Ontario to St. Louis within your budget

Compare providers for flights from Ontario to St. Louis

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.

Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Ontario to St. Louis in November.

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.

Travel insights for flights from Ontario to St. Louis

Get recent, data-driven insights about flights from Ontario to St. Louis including ideal travel times, pricing trends, and more.

How far ahead should I book a flight from Ontario to St. Louis?

Use this chart to determine the optimal time to book a round-trip flight from Ontario to St. Louis. Price data was last updated on November 15, 2024.

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

What is the cheapest time of day to fly from ONT 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 noviembre 20, 2024.

What is the cheapest day to fly from Ontario to St. Louis?

Use this chart to determine the cheapest time to fly round-trip from Ontario to St. Louis. Price data was last updated on November 18, 2024.

Weekly flight availability from Ontario to St. Louis

Rainfall in St. Louis by month

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

Temperature in St. Louis by month

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

Reviews of airlines servicing St. Louis

Read through reviews of airlines operating flights from Ontario to St. Louis, such as Frontier, Delta and United Airlines. In addition to providing an overall rating, users have also rated airlines 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 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 airports do I use to fly from Ontario to St. Louis?

What are the cheapest airlines flying from Ontario to St. Louis round-trip?

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

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

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

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

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

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 Ontario to St. Louis

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

Top 5 airlines flying from Ontario to St. Louis

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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 noviembre 20, 2024.