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Cheap flights from Ontario to St. Louis from $54

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from Ontario to St. Louis departing on 2/25. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
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Find the cheapest flights from Ontario to St. Louis

Cheap round-trip flights

These are some of the best round-trip flight deals from Ontario to St. Louis that have been recently found on momondo from popular airlines, departing in the coming months.

Cheap one-way flights

Flying one-way? These are some of the best deals recently discovered on momondo for flights from Ontario to St. Louis.

Cheap last minute flights

Planning a quick getaway from Ontario to St. Louis? These are the last-minute flight deals available now.

Cheap direct flights

If you prefer a non-stop journey, check out our latest direct flight deals to St. Louis, so you can enjoy a seamless trip without layovers.

Cheap bus & train deals from Ontario to St. Louis

Find recent round-trip train or bus tickets from Ontario to St. Louis.

All round-trip flight deals to St. Louis

The cheapest plane tickets to St. Louis found on KAYAK recently.
1:05 pm - 8:29 pmONT-STL
5h 24m1 stop
6:46 pm - 11:44 pmSTL-ONT
6h 58m1 stop
$106Frontier
Find Deal
Mon, Jan 6 - Sat, Jan 11
7:56 am - 7:31 pmONT-STL
9h 35m1 stop
6:54 pm - 12:09 amSTL-ONT
7h 15m1 stop
$108Frontier
Find Deal
Thu, Feb 6 - Sat, Feb 15
7:56 am - 7:31 pmONT-STL
9h 35m1 stop
6:43 pm - 7:26 amSTL-ONT
14h 43m1 stop
$118Frontier
Find Deal
Thu, Feb 6 - Wed, Feb 12
6:00 am - 1:18 pmONT-STL
5h 18m1 stop
5:00 pm - 10:52 pmSTL-ONT
7h 52m1 stop
$316Delta
Find Deal
Tue, Jan 14 - Tue, Jan 21
10:00 am - 10:09 pmONT-STL
10h 09m2 stops
5:12 pm - 10:45 pmSTL-ONT
7h 33m1 stop
$321American Airlines
Find Deal
Tue, Jan 14 - Tue, Jan 28
6:10 am - 4:23 pmONT-STL
8h 13m2 stops
11:38 am - 6:24 pmSTL-ONT
8h 46m2 stops
$326American Airlines
Find Deal
Tue, Jan 14 - Tue, Jan 21
7:05 am - 3:44 pmONT-STL
6h 39m1 stop
7:40 am - 12:26 pmSTL-ONT
6h 46m1 stop
$346Delta
Find Deal
Thu, Jan 9 - Tue, Jan 21
5:10 am - 12:48 pmONT-STL
5h 38m1 stop
8:27 am - 12:41 pmSTL-ONT
6h 14m1 stop
$388United Airlines
Find Deal
Tue, Feb 4 - Tue, Feb 11
5:10 am - 12:48 pmONT-STL
5h 38m1 stop
4:36 pm - 9:57 pmSTL-ONT
7h 21m1 stop
$406United Airlines
Find Deal
Wed, Jan 15 - Wed, Feb 12
2:50 pm - 12:35 amONT-STL
7h 45m2 stops
1:45 pm - 12:10 amSTL-ONT
12h 25m2 stops
$546Southwest
Find Deal
Thu, Mar 13 - Sat, Mar 15
12:59 am - 9:16 amONT-STL
6h 17m1 stop
$54Frontier
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Tue, Feb 25
1:05 pm - 8:29 pmONT-STL
5h 24m1 stop
$59Frontier
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Mon, Jan 6
7:59 am - 7:34 pmONT-STL
9h 35m1 stop
$60Frontier
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Thu, Jan 9
1:00 pm - 11:37 pmONT-STL
8h 37m1 stop
$158Delta
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Tue, Jan 7
12:48 pm - 10:56 pmONT-STL
8h 08m2 stops
$163American Airlines
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Wed, Jan 22
10:02 am - 7:30 pmONT-STL
7h 28m2 stops
$183American Airlines
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Wed, Dec 25
6:00 am - 2:37 pmONT-STL
6h 37m1 stop
$203United Airlines
Find Deal
Wed, Jan 22
6:25 am - 6:10 pmONT-STL
9h 45m2 stops
$213Southwest
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Fri, Jan 17
6:10 am - 4:47 pmONT-STL
8h 37m1 stop
$223United Airlines
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Tue, Dec 24
1:21 pm - 11:14 pmONT-STL
7h 53m2 stops
$628Delta
Find Deal
Tue, Jan 7
7:00 pm - 11:10 amONT-STL
14h 10m1 stop
6:46 pm - 10:18 amSTL-ONT
17h 32m1 stop
$288Frontier
Find Deal
Sat, Dec 21 - Sat, Jan 11
10:31 pm - 8:29 pmONT-STL
19h 58m1 stop
12:00 pm - 7:09 amSTL-ONT
21h 09m1 stop
$408Frontier
Find Deal
Thu, Dec 19 - Sun, Dec 22
7:00 pm - 11:10 amONT-STL
14h 10m1 stop
9:29 pm - 12:03 pmSTL-ONT
16h 34m1 stop
$489Frontier
Find Deal
Sat, Dec 21 - Mon, Dec 23
7:00 pm - 11:10 amONT-STL
14h 10m1 stop
9:29 pm - 12:03 pmSTL-ONT
16h 34m1 stop
$490Frontier
Find Deal
Sat, Dec 21 - Mon, Dec 23
6:50 pm - 3:47 pmONT-STL
18h 57m2 stops
4:36 pm - 8:51 pmSTL-ONT
6h 15m1 stop
$651United Airlines
Find Deal
Mon, Dec 23 - Tue, Jan 21
6:50 pm - 3:47 pmONT-STL
18h 57m2 stops
4:36 pm - 6:04 pmSTL-ONT
27h 28m2 stops
$664United Airlines
Find Deal
Mon, Dec 23 - Tue, Jan 21
11:55 am - 7:40 pmONT-STL
5h 45m1 stop
5:03 am - 8:13 pmSTL-ONT
17h 10m2 stops
Sun, Dec 22 - Tue, Jan 21
5:30 am - 1:19 pmONT-STL
5h 49m1 stop
5:00 pm - 11:53 pmSTL-ONT
8h 53m1 stop
$706Delta
Find Deal
Fri, Dec 20 - Tue, Jan 21
12:59 am - 8:52 amONT-STL
5h 53m1 stop
11:38 am - 6:24 pmSTL-ONT
8h 46m2 stops
$711American Airlines
Find Deal
Sat, Dec 21 - Tue, Jan 21
10:02 am - 7:30 pmONT-STL
7h 28m2 stops
11:38 am - 6:24 pmSTL-ONT
8h 46m2 stops
$716American Airlines
Find Deal
Sun, Dec 22 - Tue, Jan 21

Frontier flights from Ontario to St. Louis

Our best Frontier deals on Ontario to St. Louis flight tickets
Frontier
Jan 6
ONT1:05 pmOntario
5h 24m
1 stop
STL8:29 pmLambert-St Louis
Jan 11
STL6:46 pmLambert-St Louis
6h 58m
1 stop
ONT11:44 pmOntario
Frontier
Feb 6
ONT7:56 amOntario
9h 35m
1 stop
STL7:31 pmLambert-St Louis
Feb 15
STL6:54 pmLambert-St Louis
7h 15m
1 stop
ONT12:09 amOntario
Frontier
Feb 6
ONT7:56 amOntario
9h 35m
1 stop
STL7:31 pmLambert-St Louis
Feb 12
STL6:43 pmLambert-St Louis
14h 43m
1 stop
ONT7:26 amOntario

American Airlines flights from Ontario to St. Louis

Our best American Airlines deals on Ontario to St. Louis flight tickets
American Airlines
Jan 14
ONT10:00 amOntario
10h 09m
2 stops
STL10:09 pmLambert-St Louis
Jan 28
STL5:12 pmLambert-St Louis
7h 33m
1 stop
ONT10:45 pmOntario
American Airlines
Jan 14
ONT6:10 amOntario
8h 13m
2 stops
STL4:23 pmLambert-St Louis
Jan 21
STL11:38 amLambert-St Louis
8h 46m
2 stops
ONT6:24 pmOntario
American Airlines
Jan 22
ONT6:00 amOntario
7h 10m
1 stop
STL3:10 pmLambert-St Louis
Feb 8
STL5:03 amLambert-St Louis
8h 55m
2 stops
ONT11:58 amOntario

See travel insights to St. Louis from

How to get the cheapest flight ticket from Ontario to St. Louis

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

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

In general, August is the cheapest month to fly from Ontario to St. Louis. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $337. The month of September is another great option to travel to St. Louis, with average flight prices from Ontario averaging around $341.

What is the cheapest day to depart on your flight to St. Louis?

The cheapest day to depart on your flight to St. Louis is on a Tuesday when prices can be found for as low as $352. This is often the case because there is less demand to fly during this day of the week. If your travel schedule is flexible, try to avoid departing on a Sunday because tickets tend to average around $482. These prices are subject to change though, so be sure to set up a Price Alert for flights to St. Louis.

What is the cheapest time of day to depart on your flight to St. Louis?

Flying to St. Louis from Ontario in the evening is the least expensive time of day to depart. momondo users have found prices as low as $299 when looking at flights departing in the evening. At noon is when there is more demand to fly to St. Louis, so prices are often more expensive at around $419 per ticket.

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

The best time to book a flight to St. Louis from Ontario is 39 days out, which is when prices tend to be around $334. In the past 72 hours, momondo users found flights from Ontario to St. Louis for as low as $142.

Can stopping save me money on Ontario to St. Louis flights?

You could potentially save up to 43% on your flight if you consider stops on a Ontario to St. Louis flight.

How have Ontario to St. Louis flight prices changed over time?

As of December 2024, prices for Ontario to St. Louis flights are approximately 35% cheaper when compared to flights at the same time last year.

When to book flights from Ontario to St. Louis

Are you open to changing your travel dates? Check out the ideal times to fly from Ontario to St. Louis according to our flight data. Find out which month and days have the cheapest flights.
Estimated round-trip price

Cheap Ontario to St. Louis (ONT to STL) flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Ontario to St. Louis

Best Price Found

$54

Fastest flight time

5h 14m

Direct flights

None

Airports in St. Louis

1 airport
The best one-way flight to St. Louis from Ontario in the past 72 hours is $54. The best round-trip flight deal from Ontario to St. Louis found on momondo in the last 72 hours is $106.
The fastest flight from Ontario to St. Louis takes 5h 14m
There are no direct flights from Ontario to St. Louis. Popular non-direct route for this connection is Ontario Airport - Lambert-St Louis Airport.
There is 1 airport near St. Louis: Lambert-St Louis (STL)

  • How far is Ontario to Lambert-St Louis by plane?

    There are 1552.8 mi between Ontario and Lambert-St Louis. 5h 14m is a normal flight duration for this route.

  • When did momondo last update prices for flights from Ontario Airport to Lambert-St Louis Airport?

    Prices for flights from Ontario Airport to Lambert-St Louis Airport are updated daily.

  • How many operators does momondo search for flights from Ontario Airport to Lambert-St Louis Airport?

  • How old do you have to be to fly from Ontario Airport to Lambert-St Louis Airport?

    The minimum age for a child to fly alone is five, but airlines that offer an unaccompanied minor (UNMR) service may have their own age limitations. Flight duration, scheduling, and layovers are among the considerations that may influence age limits. We recommend that you double-check with the airline you are booking with for travel from Ontario Airport to Lambert-St Louis Airport.

  • What documentation or ID do you need to fly to Lambert-St Louis Airport?

    The necessary travel and health documents for your Lambert-St Louis Airport trip may vary depending on your travel plans and individual circumstances. Generally, you should have various documents, such as a national ID card or driver's license and a passport that is valid for six months beyond your scheduled arrival date. We recommend seeking advice from your airline or a trusted third party, such as IATA.

  • What is the most popular airline from Ontario to St. Louis?


Best airlines flying from Ontario to St. Louis

Compare and see reviews for airlines that fly from Ontario to St. Louis with momondo
Airline
Rating
Free Cancellation
Price
FrontierPriceFrom $104Free CancellationRating
6.1
3,479 reviews
Search Frontier flights
DeltaPriceFrom $276Free CancellationRating
8.0
8,604 reviews
Search Delta flights
American AirlinesPriceFrom $282Free CancellationRating
7.2
10,000 reviews
Search American Airlines flights
United AirlinesPriceFrom $288Free CancellationRating
7.4
9,055 reviews
Search United Airlines flights
SouthwestPriceFrom $326Free CancellationRating
8.1
4,848 reviews
Search Southwest flights

Why use momondo?

Why should I use momondo to find a flight deal from Ontario to St. Louis?

momondo collates all your flight options in one place and lets you filter them to find the perfect flight from Ontario to St. Louis. momondo saves you time and could save you money on your trip.

Can I find flights from Ontario to St. Louis with flexible booking policies on momondo?

Yes. momondo allows you to filter the results for Ontario to St. Louis flights to just show those with flexible booking policies.

How can momondo help me find flights from Ontario to St. Louis?

Once all potential Ontario to St. Louis flight options are in front of you, momondo lets you sort and filter flights based on preferences such as airline, price and flight times amongst many other options.

I’m not ready to book a flight from Ontario to St. Louis right now. Can momondo alert me if prices change?

If you are not ready to book a flight from Ontario to St. Louis now, use our insights above to find helpful tips or alternatively set up a price alert, where momondo will track prices on flights to St. Louis and let you know when they change.


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