What’s the top layover airport for flights from Ontario to St. Louis?

Las Vegas (LAS) – chosen by Cheapflights users on 71% of 1-stop itineraries from Ontario to St. Louis on Cheapflights.

What’s the fastest layover option from Ontario to St. Louis?

Flights via Phoenix (PHX) have the shortest average one-way travel time for 1-stop routes: 5h 35m.

What’s the cheapest layover airport for flights from Ontario to St. Louis?

Las Vegas (LAS) is the most affordable 1-stop option, with an average round-trip price of $328.

Which airport typically offers the quickest layover for flights from Ontario to St. Louis?

Flights via Phoenix (PHX) offer the fastest connection on this route, with an average layover time of 1h 09m.

How long is the flight from Ontario to St. Louis?

For as low as $182, Frontier can have you in St. Louis from Ontario in 11h 54m. The distance from Ontario to St. Louis is about 1541 mi.

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 $131. Additional round-trip tickets that might be worth considering are offered by Delta and American Airlines, with the lowest prices starting at $139 and $292, respectively. Frontier is priced at 63% 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 ($76), Delta ($140), and American Airlines ($158).

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.

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).

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: Frontier, Southwest or American Airlines.

Most accurate provider : When it comes to deals on Ontario-St. Louis flights, users find the pricing of CheapOair to be most consistent on Cheapflights vs. CheapOair Users can find the same prices on Ontario-St. Louis flight deals on Cheapflights vs. CheapOair >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 CheapOair the most. CheapOair 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.

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.

$73+ Flights from Ontario to St. Louis

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Find cheap flights from Ontario to St. Louis with Cheapflights

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”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.

Cheapflights Tip: The best prices from Ontario to Lambert-St Louis are usually found in September or November, booked 83 days in advance, depart on a Monday or Tuesday and return on a Tuesday

Cheap 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 December 12, 2025.

Wed 12/246:00 amONT - STL

1 stop8h 24mFrontier

Thu 1/15:19 pmSTL - ONT

1 stop5h 58mFrontier

Deal found 12/11

$183

Sat 12/276:00 amONT - STL

1 stop13h 25mFrontier

Sat 1/37:43 pmSTL - ONT

1 stop6h 16mFrontier

Deal found 12/10

$185

Mon 12/296:00 pmONT - STL

1 stop25h 25mFrontier

Mon 1/127:43 pmSTL - ONT

1 stop6h 13mFrontier

Deal found 12/10

$203

Mon 12/296:00 pmONT - STL

1 stop25h 25mFrontier

Thu 1/15:19 pmSTL - ONT

1 stop5h 58mFrontier

Deal found 12/10

$205

Thu 12/256:00 amONT - STL

1 stop8h 24mFrontier

Thu 1/15:19 pmSTL - ONT

1 stop5h 58mFrontier

Deal found 12/11

$208

Wed 12/316:00 amONT - STL

1 stop8h 24mFrontier

Thu 1/15:19 pmSTL - ONT

1 stop5h 58mFrontier

Deal found 12/11

$228

Wed 12/246:00 amONT - STL

1 stop8h 24mFrontier

Fri 1/27:43 pmSTL - ONT

1 stop6h 16mFrontier

Deal found 12/11

$237

Tue 12/236:17 pmONT - STL

1 stop20h 07mFrontier

Tue 12/3010:10 pmSTL - ONT

1 stop25h 07mFrontier

Deal found 12/11

$254

Fri 12/266:00 amONT - STL

1 stop13h 25mFrontier

Tue 12/3010:10 pmSTL - ONT

1 stop21h 05mFrontier

Deal found 12/11

$255

Wed 12/316:00 amONT - STL

1 stop8h 24mFrontier

Fri 1/210:10 pmSTL - ONT

1 stop27h 11mFrontier

Deal found 12/10

$259

Thu 12/256:00 amONT - STL

1 stop8h 24mFrontier

Fri 1/27:43 pmSTL - ONT

1 stop6h 16mFrontier

Deal found 12/11

$262

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 December 12, 2025.

Thu 1/810:18 pmONT - STL

1 stop11h 54mFrontier

Mon 1/127:43 pmSTL - ONT

1 stop6h 13mFrontier

Deal found 12/10

$182

Sat 2/141:15 pmONT - STL

1 stop8h 21mDelta

Tue 2/242:22 pmSTL - ONT

2 stops10h 15mDelta

Deal found 12/11

$298

Thu 1/86:00 amONT - STL

2 stops8h 55mUnited Airlines

Fri 1/99:57 amSTL - ONT

2 stops9h 46mUnited Airlines

Deal found 12/11

$347

Tue 2/176:14 amONT - STL

1 stop29h 37mAlaska Airlines

Mon 2/232:47 pmSTL - ONT

1 stop22h 21mAlaska Airlines

Deal found 12/11

$354

Sat 2/1411:15 amONT - STL

2 stops9h 55mSouthwest

Tue 2/248:20 amSTL - ONT

2 stops9h 45mSouthwest

Deal found 12/11

$370

Thu 1/810:18 pmONT - STL

1 stop11h 54mFrontier

Fri 1/910:16 pmSTL - ONT

1 stop18h 10mFrontier

Deal found 12/11

$193

Fri 2/207:57 amONT - STL

1 stop11h 29mFrontier

Mon 2/231:54 pmSTL - ONT

1 stop12h 05mFrontier

Deal found 12/11

$218

Wed 12/316:00 amONT - STL

1 stop8h 24mFrontier

Thu 1/15:19 pmSTL - ONT

1 stop5h 58mFrontier

Deal found 12/11

$228

Wed 3/256:00 amONT - STL

1 stop30h 11mAlaska Airlines

Sun 3/297:00 amSTL - ONT

1 stop29h 53mAlaska Airlines

Deal found 12/10

$386

Wed 12/246:00 amONT - STL

1 stop8h 24mFrontier

Sun 12/2810:10 pmSTL - ONT

1 stop25h 07mFrontier

Deal found 12/11

$343

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

Wed 12/246:00 amONT - STL

1 stop8h 24mFrontier

Thu 1/15:19 pmSTL - ONT

1 stop5h 58mFrontier

Deal found 12/11

$183

Thu 12/256:00 amONT - STL

1 stop8h 24mFrontier

Thu 1/15:19 pmSTL - ONT

1 stop5h 58mFrontier

Deal found 12/11

$208

Sat 12/276:00 amONT - STL

1 stop13h 25mFrontier

Sat 1/37:43 pmSTL - ONT

1 stop6h 16mFrontier

Deal found 12/10

$185

Mon 12/296:00 pmONT - STL

1 stop25h 25mFrontier

Mon 1/127:43 pmSTL - ONT

1 stop6h 13mFrontier

Deal found 12/10

$203

Mon 12/296:00 pmONT - STL

1 stop25h 25mFrontier

Thu 1/15:19 pmSTL - ONT

1 stop5h 58mFrontier

Deal found 12/10

$205

Thu 1/810:18 pmONT - STL

1 stop11h 54mFrontier

Mon 1/127:43 pmSTL - ONT

1 stop6h 13mFrontier

Deal found 12/10

$182

Thu 1/810:18 pmONT - STL

1 stop11h 54mFrontier

Fri 1/97:43 pmSTL - ONT

1 stop29h 31mFrontier

Deal found 12/10

$192

Thu 1/810:18 pmONT - STL

1 stop11h 54mFrontier

Sun 1/1112:37 pmSTL - ONT

1 stop7h 47mFrontier

Deal found 12/9

$217

Sat 1/103:21 pmONT - STL

1 stop18h 18mFrontier

Sat 1/173:43 pmSTL - ONT

1 stop9h 16mFrontier

Deal found 12/11

$166

Mon 1/1910:18 pmONT - STL

2 stops38h 28mFrontier

Sun 1/259:27 pmSTL - ONT

1 stop19h 14mFrontier

Deal found 12/10

$177

Thu 1/2911:04 amONT - STL

1 stop8h 02mFrontier

Sat 1/313:46 pmSTL - ONT

1 stop9h 38mFrontier

Deal found 12/10

$141

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 December 12, 2025.

Thu 1/2911:04 amONT - STL

1 stop8h 02mFrontier

Deal found 12/11

$73

Wed 12/246:00 amONT - STL

1 stop8h 24mFrontier

Deal found 12/11

$91

Sat 1/103:21 pmONT - STL

1 stop18h 18mFrontier

Deal found 12/11

$97

Fri 12/266:00 amONT - STL

1 stop13h 25mFrontier

Deal found 12/11

$98

Mon 2/232:06 pmONT - STL

2 stops38h 45mFrontier

Deal found 12/10

$112

Thu 12/256:00 amONT - STL

1 stop8h 24mFrontier

Deal found 12/11

$116

Sat 12/206:00 amONT - STL

1 stop13h 25mFrontier

Deal found 12/11

$119

Sun 12/216:45 amONT - STL

1 stop25h 17mFrontier

Deal found 12/9

$122

Thu 1/16:45 amONT - STL

1 stop25h 17mFrontier

Deal found 12/11

$123

Fri 1/96:00 amONT - STL

1 stop26h 02mFrontier

Deal found 12/10

$128

Find flight deals from Ontario to St. Louis

Most accurate provider	CheapOair 3 stars
Most trusted provider	CheapOair 3 stars
Round-trip from	$141 (Kiwi.com)
One-way from	$73 (Super.com)
Popular in	March
Cheapest in	September
Average price	$451

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

Search Deals

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

Search Deals

From Ontario to Lambert-St Louis

Search Deals

One-way flight from Ontario to Lambert-St Louis

Search Deals

Highest demand for flights based on searches. 13% potential increase in price ($55 potential increase over avg. RT price).

Search Deals

Cheapest flight prices on average. 3% potential price decrease ($11 potential savings vs. average RT price).

Search Deals

Average for round-trip flights in December 2025

Search Deals

Fly from

Fly to

Route

Depart

Return

Price

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Thu 1/8

10:18 pm-12:12 pm

1 stop11h 54m

Lambert-St Louis

Mon 1/12

7:43 pm-11:56 pm

1 stop6h 13m

$182

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Thu 1/8

10:18 pm-12:12 pm

1 stop11h 54m

Lambert-St Louis

Fri 1/9

10:16 pm-2:26 pm

1 stop18h 10m

$193

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Fri 2/20

7:57 am-9:26 pm

1 stop11h 29m

Lambert-St Louis

Mon 2/23

1:54 pm-11:59 pm

1 stop12h 05m

$218

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Wed 12/31

6:00 am-4:24 pm

1 stop8h 24m

Lambert-St Louis

Thu 1/1

5:19 pm-9:17 pm

1 stop5h 58m

$228

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Sat 2/14

1:15 pm-11:36 pm

1 stop8h 21m

Lambert-St Louis

Tue 2/24

2:22 pm-10:37 pm

2 stops10h 15m

$298

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Wed 12/24

6:00 am-4:24 pm

1 stop8h 24m

Lambert-St Louis

Sun 12/28

10:10 pm-9:17 pm

1 stop25h 07m

$343

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Thu 1/8

6:00 am-4:55 pm

2 stops8h 55m

Lambert-St Louis

Fri 1/9

9:57 am-5:43 pm

2 stops9h 46m

$347

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Tue 2/17

6:14 am-1:51 pm

1 stop29h 37m

Lambert-St Louis

Mon 2/23

2:47 pm-11:08 am

1 stop22h 21m

$354

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Sat 2/14

11:15 am-11:10 pm

2 stops9h 55m

Lambert-St Louis

Tue 2/24

8:20 am-4:05 pm

2 stops9h 45m

$370

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Wed 3/25

6:00 am-2:11 pm

1 stop30h 11m

Lambert-St Louis

Sun 3/29

7:00 am-10:53 am

1 stop29h 53m

$386

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/10

Showing 1-10 of 18 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 December.

Provider	Price Accuracy	Trust Score*
Expedia	Price Accuracy2 stars	Trust Score*3 stars
eDreams	Price Accuracy3 stars	Trust Score*3 stars
FlightHub	Price Accuracy3 stars	Trust Score*1 star
Priceline	Price Accuracy1 star	Trust Score*3 stars
JustAirTicket	Price Accuracy-	Trust Score*1 star
CheapOair	Price Accuracy3 stars	Trust Score*3 stars
Gotogate	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 CheapOair to be most consistent on Cheapflights vs. CheapOair Users can find the same prices on Ontario-St. Louis flight deals on Cheapflights vs. CheapOair >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 CheapOair the most. CheapOair 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.

Cheapflights Insights

Everything you need to know about your flight from Ontario to St. Louis

Prices

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 82 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 $71). Flying from Ontario to St. Louis in March is currently the most expensive (average of $220). 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 59% 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.

Reviews of airlines servicing St. Louis

Get a feel of what it's like to fly with Southwest, Delta, and United Airlines from Ontario to St. Louis by reading reviews from past customers. Users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.

Southwest

7.9

Good

4,253 reviews

Reviews

1 / 20

10.0

Excellent

William Drew,Nov 2025

SJC - HNL

Flight crew was amazing! Usually they're very good on Southwest, but this crew went above and beyond. I have never ever seen so many rounds of drink service on a flight before.

Southwest

7.9

Good

4,253 reviews

Southwest

7.9

Good

4,253 reviews

Reviews

1 / 20

10.0

Excellent

William Drew,Nov 2025

SJC - HNL

Flight crew was amazing! Usually they're very good on Southwest, but this crew went above and beyond. I have never ever seen so many rounds of drink service on a flight before.

Delta

7.9

Good

8,008 reviews

Southwest

7.9

Good

4,253 reviews

Reviews

1 / 20

10.0

Excellent

William Drew,Nov 2025

SJC - HNL

Flight crew was amazing! Usually they're very good on Southwest, but this crew went above and beyond. I have never ever seen so many rounds of drink service on a flight before.

United Airlines

7.4

Good

9,095 reviews

Southwest

7.9

Good

4,253 reviews

Reviews

1 / 20

10.0

Excellent

William Drew,Nov 2025

SJC - HNL

Flight crew was amazing! Usually they're very good on Southwest, but this crew went above and beyond. I have never ever seen so many rounds of drink service on a flight before.

American Airlines

7.2

Good

11,050 reviews

Southwest

7.9

Good

4,253 reviews

Reviews

1 / 20

10.0

Excellent

William Drew,Nov 2025

SJC - HNL

Flight crew was amazing! Usually they're very good on Southwest, but this crew went above and beyond. I have never ever seen so many rounds of drink service on a flight before.

Frontier

5.8

Fair

3,084 reviews

Southwest

7.9

Good

4,253 reviews

Reviews

1 / 20

10.0

Excellent

William Drew,Nov 2025

SJC - HNL

Flight crew was amazing! Usually they're very good on Southwest, but this crew went above and beyond. I have never ever seen so many rounds of drink service on a flight before.

Related info for your journey

How long is the flight from Ontario to St. Louis?
For as low as $182, Frontier can have you in St. Louis from Ontario in 11h 54m. The distance from Ontario to St. Louis is about 1541 mi.
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 $131. Additional round-trip tickets that might be worth considering are offered by Delta and American Airlines, with the lowest prices starting at $139 and $292, respectively. Frontier is priced at 63% 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 ($76), Delta ($140), and American Airlines ($158).
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 $71). Flying from Ontario to St. Louis in March is currently the most expensive (average of $220). 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

Edwardsville

O'Fallon

Fairview Heights

Maryland Heights

Collinsville

Swansea

Eureka

Glencoe

St. Peters

Chesterfield

Alton

Farmington

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Other flights to St. Louis

Top 5 airlines flying from Ontario to St. Louis

Airline	Cheapest	Average	Flexibility	On-time
Frontier	Cheapest$146	Average$227	FlexibilityNo cancel fee	On-time62%
Delta	Cheapest$286	Average$401	FlexibilityNo cancel fee	On-timeN/A
United Airlines	Cheapest$292	Average$468	FlexibilityNo cancel fee	On-time69%
American Airlines	Cheapest$292	Average$402	FlexibilityNo cancel fee	On-time71%
Southwest	Cheapest$346	Average$425	FlexibilityNo cancel fee	On-time63%

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$73+ 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 1/29. 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

Cheapflights Tip: The best prices from Ontario to Lambert-St Louis are usually found in September or November, booked 83 days in advance, depart on a Monday or Tuesday and return on a Tuesday

Cheap 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 December 12, 2025.

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 December 12, 2025.

Find flight deals from Ontario to St. Louis

Most accurate provider

Most trusted provider

Round-trip from

One-way from

Popular in

Cheapest in

Average price

Cheapflights Fare Finder

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

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 December.

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.

Cheapflights Insights

Everything you need to know about your flight from Ontario to St. Louis

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

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?

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

What’s the top layover airport for flights from Ontario to St. Louis?

What’s the cheapest layover airport for flights from Ontario to St. Louis?

What’s the fastest layover option from Ontario to St. Louis?

Which airport typically offers the quickest layover for flights from Ontario to St. Louis?

Reviews of airlines servicing St. Louis

Get a feel of what it's like to fly with Southwest, Delta, and United Airlines from Ontario to St. Louis by reading reviews from past customers. 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.

How long is the flight 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?

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Alternative routes for Ontario to St. Louis

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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 December 12, 2025.