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ONT - STL

$73 Find cheap flights from Ontario to St. Louis

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Ontario to St. Louis departing on 8/11. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
0 bags
Sat 6/8
Sat 6/15

Search hundreds of travel sites at once for deals on flights to St. Louis

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Ontario to St. Louis, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Ontario to St. Louis, as well as popular online travel agencies
In the last 7 days travelers have searched 43,895,468 times on KAYAK, and here is why:

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Cheap flight deals from Ontario to St. Louis (ONT-STL)

Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Ontario to St. Louis that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices and deals for you by selecting your travel dates.
Choose your dates
11:07 pm - 10:13 amONT-STL
9h 06m1 stop
8:04 pm - 11:59 pmSTL-ONT
5h 55m1 stop
$126Frontier
Find Deal
Thu, May 30 - Mon, Jun 3
12:59 am - 10:06 pmONT-STL
19h 07m1 stop
8:04 pm - 11:59 pmSTL-ONT
5h 55m1 stop
$130Frontier
Find Deal
Wed, May 29 - Mon, Jun 3
12:59 am - 1:09 pmONT-STL
10h 10m1 stop
7:23 pm - 4:05 pmSTL-ONT
22h 42m1 stop
$132Frontier
Find Deal
Mon, May 20 - Tue, May 28
6:15 am - 5:14 pmONT-STL
8h 59m2 stops
2:35 pm - 9:44 pmSTL-ONT
9h 09m1 stop
$369American Airlines
Find Deal
Fri, Sep 27 - Tue, Oct 8
11:22 am - 12:56 amONT-STL
11h 34m2 stops
6:25 pm - 11:42 pmSTL-ONT
7h 17m1 stop
$378Delta
Find Deal
Wed, Jun 5 - Wed, Jun 12
6:15 am - 5:14 pmONT-STL
8h 59m2 stops
4:20 pm - 9:42 pmSTL-ONT
7h 22m1 stop
$379American Airlines
Find Deal
Thu, Sep 26 - Wed, Oct 9
12:59 am - 9:29 amONT-STL
6h 30m1 stop
2:56 pm - 11:59 pmSTL-ONT
11h 03m2 stops
Tue, Jun 11 - Sat, Jun 15
8:41 pm - 10:42 amONT-STL
12h 01m1 stop
2:56 pm - 11:59 pmSTL-ONT
11h 03m2 stops
Wed, Jun 12 - Sat, Jun 15
5:00 pm - 12:58 amONT-STL
5h 58m1 stop
7:55 am - 12:17 pmSTL-ONT
6h 22m1 stop
$445Delta
Find Deal
Tue, Jun 11 - Sun, Jun 23
6:25 pm - 2:14 pmONT-STL
17h 49m2 stops
9:05 am - 8:48 pmSTL-ONT
13h 43m1 stop
$552United Airlines
Find Deal
Wed, Jun 12 - Sun, Jun 16

Flights from Ontario to St. Louis - Travel Insights & Trends

Get data-powered insights and trends into flights from Ontario to St. Louis to help you find the cheapest flights, the best time to fly and much more.

What’s the cheapest day of the week to fly from Ontario to St. Louis?

The average price of all flights from Ontario to St. Louis clicked on KAYAK for each day over the last 12 months.
Your flight ticket price will generally be cheaper if you fly to St. Louis on a Saturday and more expensive on a Monday. On your return trip to Ontario, you should consider flying back on a Thursday, and avoid Fridays for better deals.

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

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for flights from Ontario to St. Louis, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.
The cheapest month for flights from Ontario to St. Louis is January, where tickets cost $376 on average. On the other hand, the most expensive months are July and June, where the average cost of tickets is $467 and $456 respectively.

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

To calculate daily average prices, KAYAK takes all prices for each day before departure over the last year for flights from Ontario to St. Louis, removes the top 0.1% to account for outliers, and then takes the average of all the values for each month.
To get a below average price on the flight from Ontario to St. Louis, you should book around 2 weeks before departure. For the absolute cheapest price, our data suggests you should book 47 days before departure.

Which airlines provide the cheapest flights from Ontario to St. Louis?

The cheapest price for the route for each airline clicked by KAYAK users in the last 72 hours.
In the last 72 hours, the cheapest one-way ticket from Ontario to St. Louis found on KAYAK was with Frontier for $73. Frontier proposed a round-trip connection from $126 and American Airlines from $369.

Good to know

Low season

January

High season

April

Cheapest flight

$73
Best time to beat the crowds with an average 15% drop in price.
Most popular time to fly and prices are also 7% lower on average.
Flight from Ontario to St. Louis

When to book flights from Ontario to St. Louis

Are your dates flexible? Find out the best times to travel from Ontario to St. Louis based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking flights from Ontario to St. Louis

  • What is the cheapest flight from Ontario to St. Louis?

    In the last 3 days, the lowest price for a flight from Ontario to St. Louis was $73 for a one-way ticket and $126 for a round-trip.

  • Do I need a passport to fly between Ontario and St. Louis?

    No

  • Which aircraft models fly most regularly from Ontario to St. Louis?

    We unfortunately don’t have that data for this specific route.

  • Which airline alliances offer flights from Ontario to St. Louis?

    oneworld, SkyTeam, and Star Alliance are the airline alliances operating flights between Ontario and St. Louis, with oneworld being the most commonly used for this route.

  • Which is the best airline for flights from Ontario to St. Louis, Delta or United Airlines?

    The two airlines most popular with KAYAK users for flights from Ontario to St. Louis are Delta and United Airlines. With an average price for the route of $452 and an overall rating of 8.0, Delta is the most popular choice. United Airlines is also a great choice for the route, with an average price of $439 and an overall rating of 7.4.

  • How does KAYAK find such low prices on flights from Ontario to St. Louis?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Ontario to St. Louis.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Ontario to St. Louis?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to St. Louis from Ontario is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Ontario to St. Louis?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to St. Louis with an airline and back to Ontario with another airline. Booking your flights between Ontario and STL can sometimes prove cheaper using this method.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Ontario to St. Louis?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to St. Louis from Ontario up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

See more FAQs

Top 4 airlines serving from Ontario to St. Louis

 
See real verified KAYAK customer reviews for airlines flying from Ontario to St. Louis. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Ontario to St. Louis? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
DeltaOverall score based on 10778 reviews
8.6Crew
8.0Entertainment
7.9Comfort
7.4Food
8.2Boarding
Airline reviews

There was a loud squeaky sound the whole time we were flying.

6.0 GoodEliza, Apr 2024SAN - LAX
Read more about Delta reviews

There was a loud squeaky sound the whole time we were flying.

On 2 different flights the wifi was horrible and there was no drink or snack service.

I didn’t not like that I could not select my seat and ended up with the worse seat.

The landing was bad and the hostess came two times and i was sleeping but when she served the person that nexts to me I woke up and she didn’t even asked me if I need any drink or snacks two times!!!!

Plane was late because of a mechanical malfunction and the food listed as available was not. Flight attendants seem over worked and under paid. They just done seem happy. And that can be seen in their faces.

Waited 3 hours on a plane to de-ice due to manpower issues. Waited another hour and a half once we landed because of a gate issue. Missed my connections. Created. A total of 13 hours of delay.

There was no FREE wi-fi nor entertainment screens at all.

Great, on time departure, friendly and accommodating crew, great leg room, Smith flight

Plane was turned around due to fog half way into the flight, Delta did not properly direct passengers to stay on same flight and instead failed to properly rebook on Alaska

Like most domestic flights in the US, you are basically on your own with this airline when it comes to food, so be sure to purchase meals and drinks ahead of time or expect to arrive starving and dehydrated (like I was).

I paid $380 for my one-way ticket from California to Minnesota. The fair did not include online check-in. I received instructions from their app to check in at a kiosk. At the kiosk, the boarding pass would not print until an actual person came to verify that I had a personal item and not a carry-on item, On the plane, the person next to me was drunk and allowed to continue to order alcohol. United is garbage I’d rather fly spirit.

Do not like the feeling of being in the basic economy. Everyone should feel good no matter what.

Terrible! The plane was old and you are required to connect your own device to their Wi-Fi rather than have entertainment options in the back of the seat in front of you. The Wi-Fi went out during the flight and there was only one plug for the devices every two seats. Three out of five surrounding my family did not work. The seats and spaces under them were so small I could not fit my backpack, which I’ve always brought on flights and fit before no problem. The crew were unpleasant and patronizing.

Last minute gate change nearly caused us to miss our flight. Change was not announced or displayed in the main board at the old gate. Terrible communication. When we landed we had to wait 20 minutes because there was another plane at the assigned gate. Not the crew’s fault, but adding 20 minutes to a 45 minute flight sucked.

Due to one crew member not showing up to work, our flight was significantly delayed causing us to miss our connecting flight in Houston to Mississippi causing us to be delayed by more than 6 hours and missing our event all together. Very disappointing. All because ONE crew member called in sick. United did grant us a $15 meal voucher, which was a small but appreciated concession that I wasn’t able to use because I ordered my lunch and paid for it before applying the concession, and the staff said it was too late to use it. Ugh! We also had a TWO delay coming back from Mississippi, but that was on American Airlines and it was due to weather, so not their fault. Anyway, not at all impressed with United’s handling of our flight and the HUGE disappointment of missing our important family event for our 90 year old mother. All that money and all that stress and emotions for nothing. Having to wait the hour to bring an employee from LAX seemed like something that should not have happened. Why don’t you have a local back-up? Santa Ana is not a little airport in a rural area.

Crew was great and did their best to make us comfortable and captain came out at the beginning to announce why the flight was delayed, weather situation up ahead, and kept us updated throughout the flight.

United WiFi is consistently unusable (it can take 10 mins to load a single web page). If you need Wifi to do work, be prepared to lose half a day of productivity.

Awful. I got stuck next to a person carrying a dog and behind someone with a dog. People need to board these dogs downstairs. The cabin is crowded enough with your pets

Packed in like sardines, very uncomfortable. Sitting the aisle my shoulder was rammed into numerous times by rushing flight attendants. Also flight was very cold.

the head jack on my seat didn't work and the power outlet didn't work for my seat

Horrible - they lied to me about baggage & boarding, even though I specifically spoke to their agents the day before my flight about my issue. When I showed up they did not let me board and stranded me at my airport until I bought a new flight with money I did not have to spend.

The experience was great and much better than the flight going out. of course I was in first class but the service was excellent

Comfort of seats, ease of boarding. Food selection could be better

Food options were limited which is absolutely embarrassing for a Flight of this size The staff did not come around as much and I am not accustomed to such poor service from American Airlines Drinks I believe were limited to soda and water

Crew were attentive and friendly. Flight was smooth and early! I enjoyed the less crowded plane. Thank you!

We are gluten free, there were not any available complimentary gluten free options.

Flight delayed, boarding time kept changing, not good. Nee firm information given each time.

No meal on a cross country flight? SFO-MiA is pretty much the definition of a coast to coast flight. No meal provided. Sky high wi-fi rates too. Stop nickel and diming your customers.

The staff was unprofessional and didn’t communicate very well. The boarding process was very disheveled, potentially due to a power outage the previous day but there was no contingency plan to properly get passengers boarded the following day. Once boarded the aircraft stayed on the tarmac for over 45 minutes due to high winds. The communication was sporadic but an announcement was finally made an additional 30 minutes later that the flight was cancelled but we couldn’t get off the plane. Prior to deplaning one of the gate agents came on the plane and made an announcement for everyone to pickup their checked bags and take a card to rebook a new reservation because they didn’t have adequate staff. Flights were missed, passengers went to different airports and there was little to no assistance from AA.

Apart from the delay due to unforeseen circumstances. The leg from sjc to dfw was fine. It was the leg from dfw to orf that we encountered issues mainly due to the flight attendant crew not being friendly. We had two small children and we needed some assistance to warm up milk so the baby would sleep. The crew just didn’t get it and made things very difficult. One made a remark that the baby’s dirty diaper smell was a “gift” to the plane in a rude way. Normally I’d brush that off as a funny comment if the rest of the trip the attendants were helpful or understanding of the difficulty we faced. But that wasn’t the case. We were met with rudeness on the second leg. Whereas on the first leg the crew were so nice and helpful.

Our flight was delayed an hour, then when we got to board our flight finally, we were waiting in our seats for take off for 45 minutes before it was communicated that there was a maintenance issue therefore we waited on the plane for over an hour while that was resolved. We did not get to Phoenix until almost 3 hours after we were originally supposed to. This was the first and last time I will be flying Frontier.

There were 3 leg for the trip and each leg was delayed by 90 minutes or more. The boarding process takes forever with people waiting on the jetway even though most folks do not have carry-on. The whole process is poorly managed.

They cancelled the flight then did nothing to help us rebook. It was awful - I won’t fly with them again

The process of buying the ticket and navigating all the hidden charges that Frontier throws at you was a terrible experience. The actual airport experience and flying was fine.

The truck that was refueling the plane drove away with the hose still connected to the plane and ripped part of the plane off with it

Terrible. Seats are bad and the baggage policy is inconsistent

Better than I expected but I did pay for a seat and carry on bags ahead of time.

I hope to avoid flying with them in the future. First flight got cancelled then got stuck with a 13 hour layover in Denver. The process was long and frustrating to many people.

Flight was delayed on the runway for 40 minutes the crew did not even offer even water to passengers to compensate for the flight delayed. The flight was delayed due to aircraft mechanical issues. Worst customer service ever

The flight was delayed and I had to cancel because I would have missed my connection and there were no other flights for the next two days. They also lost my bag!!

Book cheap flights from Ontario to St. Louis

Recent one-way flight deals

 
Only flying one-way? Below are some of the best one-way flight deals from Ontario to St. Louis found on KAYAK in the last 72 hours.
8/11Sun
1 stopFrontier
6h 48mONT-STL
$73
5/25Sat
1 stopFrontier
10h 03mONT-STL
$76
10/23Wed
1 stopAmerican Airlines
11h 59mONT-STL
$173
6/4Tue
2 stopsAmerican Airlines
7h 58mONT-STL
$182
8/12Mon
1 stopDelta
7h 53mONT-STL
$202
6/11Tue
2 stopsAlaska Airlines
14h 49mONT-STL
$249
7/12Fri
2 stopsUnited Airlines
18h 11mONT-STL
$262
7/2Tue
2 stopsAlaska Airlines
14h 59mONT-STL
$264
10/24Thu
2 stopsUnited Airlines
18h 37mONT-STL
$290
5/16Thu
2 stopsDelta
11h 26mONT-STL
$352

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Last minute flights from Ontario to St. Louis

Last minute flight, train and bus deals

 
These last-minute flight deals are the cheapest flights found on KAYAK in the last 72 hours for flights from Ontario to St. Louis that are departing in the next 10 days.
5/14Tue
multi-stopFrontier
7h 20mONT-STL
5/15Wed
multi-stopFrontier
7h 21mSTL-ONT
$140
5/14Tue
multi-stopFrontier
6h 48mONT-STL
5/16Thu
multi-stopFrontier
26h 53mSTL-ONT
$146
5/13Mon
multi-stopFrontier
12h 51mONT-STL
5/15Wed
multi-stopFrontier
7h 21mSTL-ONT
$147
5/11Sat
multi-stop
14h 02mONT-STL
5/15Wed
multi-stop
7h 21mSTL-ONT
$489
5/10Fri
multi-stop
6h 52mONT-STL
5/15Wed
multi-stop
15h 28mSTL-ONT
$598
5/14Tue
multi-stopUnited Airlines
8h 31mONT-STL
5/15Wed
multi-stopUnited Airlines
14h 06mSTL-ONT
$763
5/14Tue
multi-stopUnited Airlines
5h 26mONT-STL
5/15Wed
multi-stopUnited Airlines
12h 43mSTL-ONT
$799
5/14Tue
multi-stopAmerican Airlines
11h 39mONT-STL
5/15Wed
multi-stopAmerican Airlines
11h 28mSTL-ONT
$866
5/14Tue
multi-stopAlaska Airlines
10h 39mONT-STL
5/15Wed
multi-stopAlaska Airlines
8h 53mSTL-ONT
$1,412
5/12Sun
multi-stopAlaska Airlines
10h 39mONT-STL
5/15Wed
multi-stopAlaska Airlines
8h 53mSTL-ONT
$1,422

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Ontario - St. Louis Flights

Departure:

Ontario (undefined)United States

Destination:

St. Louis (STL)United States

Return flight deals:

St. Louis - Ontario

Cabin classes: