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ONT - STL

Find cheap flights from Ontario to St. Louis from $45

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 4/24. 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
Sun 4/28
Sun 5/5

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 46,342,885 times on KAYAK, and here is why:

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Cheap flight deals from Ontario to St. Louis

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
12:59 am - 3:50 pmONT-STL
12h 51m1 stop
8:04 pm - 11:59 pmSTL-ONT
5h 55m1 stop
$99Frontier
Find Deal
Mon, Apr 22 - Wed, Apr 24
10:59 pm - 10:18 amONT-STL
9h 19m1 stop
12:59 pm - 4:59 pmSTL-ONT
6h 00m1 stop
$100Frontier
Find Deal
Fri, Apr 19 - Sat, Apr 20
9:04 pm - 1:58 pmONT-STL
14h 54m1 stop
8:04 pm - 7:03 amSTL-ONT
12h 59m2 stops
Thu, Apr 11 - Mon, Apr 15
7:20 pm - 9:47 amONT-STL
12h 27m2 stops
5:02 pm - 11:20 amSTL-ONT
20h 18m1 stop
Fri, Apr 12 - Mon, Apr 15
11:20 am - 12:46 amONT-STL
11h 26m2 stops
6:50 pm - 11:59 pmSTL-ONT
7h 09m1 stop
$350Delta
Find Deal
Fri, May 3 - Sun, May 5
5:45 am - 1:31 pmONT-STL
5h 46m1 stop
6:50 pm - 11:59 pmSTL-ONT
7h 09m1 stop
$458Delta
Find Deal
Thu, Apr 18 - Thu, Apr 18
12:55 pm - 11:00 pmONT-STL
8h 05m2 stops
6:37 pm - 11:57 pmSTL-ONT
7h 20m1 stop
$463American Airlines
Find Deal
Fri, Apr 19 - Mon, Apr 22
6:00 am - 4:25 pmONT-STL
8h 25m1 stop
9:05 am - 5:28 pmSTL-ONT
10h 23m1 stop
$495United Airlines
Find Deal
Sun, May 26 - Wed, May 29
10:45 am - 12:41 pmONT-STL
23h 56m2 stops
6:00 am - 8:40 pmSTL-ONT
16h 40m2 stops
$506United Airlines
Find Deal
Tue, Apr 23 - Wed, May 1
10:00 am - 7:29 pmONT-STL
7h 29m2 stops
5:00 am - 11:58 amSTL-ONT
8h 58m1 stop
$575American Airlines
Find Deal
Thu, Apr 11 - Sun, Apr 14

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 February, where tickets cost $420 on average. On the other hand, the most expensive months are December and March, where the average cost of tickets is $503 and $492 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 68 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 $45. Frontier proposed a round-trip connection from $99 and Delta from $350.

How long does a flight from Ontario to St. Louis take?

There are no direct flights for this route listed on KAYAK. The shortest multi-flight duration is 5h 21m.

Good to know

Low season

February

High season

May

Cheapest flight

$45
Best time to beat the crowds but there is an average 3% increase in price.
Most popular time to fly with an average 21% increase in price.
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 $45 for a one-way ticket and $99 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, Star Alliance, and SkyTeam 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 $481 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

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 KAYAK reviews.
8.0
DeltaOverall score based on 11402 reviews
80entertainment
82boarding
79comfort
81overall
75food
86crew
Airline reviews

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

Read more about Delta

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).

You need to be a hacker to get the (Free) WiFi

I guess they don’t serve drinks on planes anymore

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

Left 2 hours later for delayed I had to take care a kid with special need since people don’t want to move to accommodate the rest of the family. . It wasn’t bad but that made me upset that people can be that selfish.

For a 22 minute flight all you expect is for it to be safe and comfortable

Flight was on time. Staff were friendly. I paid for Economy Plus but was required to check my standard carry-on luggage due to lack of space on the aircraft. This cost me 30 minutes, unexpectedly, in waiting at the baggage claim. This experience did not meet my expectations.

Wouldn’t let me check in said couldn’t find a ticket had to wait very long Time

Airline did not explain reasons why flight was delayed two hours. Explanations were badly needed and rarely provided. Problem seemed to clearly be the airline’s fault and not the fault of the weather or airport.

Very uncomfortable seats and seat backs, and I am only 5’9”. Delayed due to crew issues, spent a long time with no ventilation. Teeny overhead bins. Wifi worked well. Arrived safely.

I was delighted that we were able to get on the 4:40 pm flight rather than our original booking at 6:55 pm!! Other than that, the flight was comfortable and landed early😊

We waited too long to get water while the plane was on the Tarmac awaiting de-icing.

I liked that we arrived earlier, you could improve your snacks give away

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.

Flight From PHX to CVG was on time, very professional staff

Flight was delayed and missed connecting flight. Did not give warning about delay until we showed up at the airport. Not good.

The usual wait at Columbus once you land to get to an open gate (20 minutes) and then the usual 30 minutes for your luggage to appear.

Nothing, flight was supposed to leave at 758 am. My flight didn’t leave until 430 pm. Spent the whole day at the airport.

Everything was very good EXCEPT the food, on a five and a half hour trip. They only gave to us was snacks in first class. They didn't give us pillows or blankets.

It was wonderful upgrading to first. Plane was so cold thou. Crew was great. Wish there was a food option in first for such a long flight. Doesnt matter the time of day. Chintzy.

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!!

My first time to fly Frontier and loved it! Boarding was super easy as we only had personal items. Crew was helpful and funny and the plane was clean. Pilot was also great at landing the plane smoothly.

The experience was terrible. The flight boarded late, then after leaving the gate the plane had had to return to the gate for fuel. After 2 hours on the plane, the flight was canceled. The reasons given for the cancelation didn't sound truthful. and different reasons were given. My 15 year old daughter was flying alone on this flight. When they all disembarked the plane she kept asking the crew what she was supposed to do. No one even gave her the courtesy of a response. No one. It took another 4.75 hrs to be out of customs and baggage. She was re-booked the following day. That flight departed 2 hours late. After all of that, they offered a measly $100 flight voucher with an expiry date of 3 months! All in all a terrible experience. We won't be using Frontier again in the future.

late late late late no accountability no refund no adjustment no reasonable solution

This isna terribly run airlines. If you're one minute late, they will deny your ticket. Don't waste your time or money

Flight was delayed for more than 3 hours, crew at ONT airport was rude, and when we got to DFW the airplane had an issue landing, we had to be taxied to the terminal, and the luggage was hold until the next day.

Several delays in a row totaling two hours with no information announcements and no explanations given. Rude and unapologetic onboard flight attendant addressing those of us in overpriced emergency exits as if we were idiots. It had been a while since I felt treated like cattle. I will do my best to avoid Frontier as much as possible in the future.

Well the first and worst thing is that you have to pay for a carry on bag. Which they tell you if you don’t read it when you book your flight. You can do it through their website at the ticket area. The staff in Sacramento were RUDE and wouldn’t answer any questions. I will NEVER book with Frontier again. Save the headache and book with Southwest so you don’t have to pay to carry your own bag on the plane. It cost me 41 and 37. On top of my fare. Which by the way went up as soon as I booked it. First it said 38 and then wouldn’t you know it, once I was ready to book, it went up to 78.

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.
4/24Wed
1 stopFrontier
7h 39mONT-STL
$45
5/3Fri
1 stopFrontier
9h 19mONT-STL
$61
4/7Sun
3 stops
45h 33mONT-STL
$168
4/4Thu
2 stops
42h 14mONT-STL
$219
4/25Thu
2 stopsAlaska Airlines
14h 59mONT-STL
$227
5/2Thu
2 stopsAmerican Airlines
8h 05mONT-STL
$269
5/3Fri
2 stopsAlaska Airlines
15h 00mONT-STL
$274
3/31Sun
1 stopAmerican Airlines
7h 41mONT-STL
$383
6/24Mon
2 stopsUnited Airlines
24h 00mONT-STL
$519
4/7Sun
2 stopsUnited Airlines
8h 29mONT-STL
$722

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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.
4/2Tue
multi-stopFrontier
10h 15mONT-STL
4/3Wed
multi-stopFrontier
22h 59mSTL-ONT
$191
4/2Tue
multi-stopFrontier
10h 15mONT-STL
6/8Sat
multi-stopFrontier
15h 37mSTL-ONT
$215
4/2Tue
multi-stop
32h 13mONT-STL
4/5Fri
multi-stop
14h 13mSTL-ONT
$393
4/1Mon
multi-stop
14h 53mONT-STL
4/5Fri
multi-stop
14h 13mSTL-ONT
$710
4/1Mon
multi-stopAmerican Airlines
5h 55mONT-STL
4/3Wed
multi-stopAmerican Airlines
5h 48mSTL-ONT
$718
4/1Mon
multi-stopAmerican Airlines
7h 41mONT-STL
4/3Wed
multi-stopAmerican Airlines
8h 42mSTL-ONT
$723
3/31Sun
multi-stopUnited Airlines
6h 16mONT-STL
4/7Sun
multi-stopUnited Airlines
31h 39mSTL-ONT
$735
3/31Sun
multi-stopUnited Airlines
6h 16mONT-STL
4/7Sun
multi-stopUnited Airlines
31h 39mSTL-ONT
$736
3/31Sun
multi-stopDelta
5h 41mONT-STL
4/7Sun
multi-stopDelta
7h 11mSTL-ONT
$752
4/3Wed
multi-stopDelta
8h 12mONT-STL
4/7Sun
multi-stopDelta
6h 44mSTL-ONT
$1,114

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Ontario - St. Louis Flights

Departure:

Ontario (ONT)United States

Destination:

St. Louis (STL)United States

Return flight deals:

St. Louis - Ontario

Cabin classes: