$89+ Cheap flights from St. Louis to Ontario (STL - ONT)
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 5/4. Fares are subject to change and may not be available on all flights or dates of travel.
Find cheap flights from St. Louis to Ontario 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 Lambert-St Louis to Ontario are usually found in February or June, booked 16 days in advance, depart on a Tuesday or Wednesday and return on a Monday
Cheap flight deals from St. Louis to Ontario
Discover tips and strategies to find the most affordable flight options for your journey from St. Louis (STL) to Ontario (ONT). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated April 4, 2025.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $240 (Frontier) |
One-way from | $89 (Trip.com) |
Popular in | March |
Cheapest in | February |
Average price | $267 |
Find flight deals from St. Louis to Ontario
Cheapest flights from St. Louis to OntarioExplore the most affordable flight options available from St. Louis to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on April 4, 2025.
Explore the most affordable flight options available from St. Louis to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on April 4, 2025.
This Frontier deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
This Delta deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
This Expedia deal was found by Cheapflights users on 4/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
This American Airlines deal was found by Cheapflights users on 4/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
This United Airlines deal was found by Cheapflights users on 4/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
This Alaska Airlines deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
This Southwest deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Cheapflights Fare Finder
Customize your flight search to find flights from St. Louis to Ontario that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated April 4, 2025.
Use the filters below to find and compare flights from St. Louis to Ontario that are best for you.
Fly from
Fly to
Route
Depart
Return
Price
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Mon 4/28
6:58 pm-11:59 pm
1 stop7h 01m
Ontario
Thu 5/8
12:59 am-9:09 am
1 stop6h 10m
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Tue 4/29
6:00 am-10:57 am
1 stop6h 57m
Ontario
Wed 5/7
4:57 pm-12:33 am
1 stop5h 36m
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Fri 5/9
6:53 pm-11:59 pm
1 stop7h 06m
Ontario
Mon 5/12
6:24 pm-9:49 am
2 stops13h 25m
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Thu 5/29
5:19 am-11:50 am
2 stops8h 31m
Ontario
Mon 6/2
11:59 pm-9:54 am
1 stop7h 55m
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Tue 7/1
5:15 am-12:14 pm
2 stops8h 59m
Ontario
Tue 7/8
6:00 am-4:29 pm
2 stops8h 29m
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Wed 4/30
6:30 am-8:29 pm
1 stop15h 59m
Ontario
Tue 5/6
11:46 am-11:59 pm
1 stop10h 13m
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Fri 6/6
3:45 pm-8:00 pm
1 stop6h 15m
Ontario
Sun 6/8
6:15 am-5:30 pm
2 stops9h 15m
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Sun 5/4
9:55 pm-7:24 am
1 stop11h 29m
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Thu 5/8
5:00 am-12:05 pm
2 stops9h 05m
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Tue 5/6
6:30 am-10:51 am
1 stop30h 21m
Compare providers for flights from St. Louis to Ontario
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 St. Louis to Ontario in April.
| Provider | Price Accuracy | Trust Score* |
|---|---|---|
| Price Accuracy1 star | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy1 star | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars |
- Most accurate provider: When it comes to deals on St. Louis-Ontario flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on St. Louis-Ontario flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from St. Louis-Ontario flight searches over the past month and is updated monthly.
- Most trusted provider: When it comes to deals on St. Louis-Ontario 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 St. Louis-Ontario 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 St. Louis to Ontario
Have a flexible travel schedule? Discover the best time to fly to Ontario from St. Louis with our price prediction graph.
Cheapflights Insights
Everything you need to know about your flight from St. Louis to Ontario
How far ahead should I book a flight from St. Louis to Ontario?
Use this chart to determine the optimal time to book a round-trip flight from St. Louis to Ontario. Price data was last updated on March 28, 2025.
The price you pay for your flight from St. Louis to Ontario may vary depending on when you book. For the best chance of a lower fare, look to book 16 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.
What is the cheapest month to book a flight from St. Louis to Ontario?
Currently, August is the cheapest month in which you can book a flight from St. Louis to Ontario (average of $246). Flying from St. Louis to Ontario in March is currently the most expensive (average of $328). 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 STL to ONT?
Find hourly flight availability from St. Louis to Ontario. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated April 4, 2025.
It’s optimal to fly from St. Louis to Ontario in the afternoon. By choosing this option you can save up to 19% on the cost of your flight, compared to a flight in the morning.
What is the cheapest day to fly from St. Louis to Ontario?
Use this chart to determine the cheapest time to fly round-trip from St. Louis to Ontario. Price data was last updated on December 16, 2024.
Travelers seeking maximum savings on their St. Louis to Ontario flight should consider departing on Monday evenings when fares are most often at their lowest. Sunday mornings flights should be avoided if possible as fares are typically the most expensive at this time.
Rainfall in Ontario by month
Plan your trip to Ontario by taking into account the average rainfall totals by month.
In terms of precipitation, rainfall in Ontario ranges from 0.1 - 3.4 inches per month. February is typically the wettest month, when rainfall can reach 3.4 in. June is typically the driest time to visit Ontario when rainfall is around 0.1 in.
Temperature in Ontario by month
Plan your trip to Ontario by taking into account the average temperature totals by month.
If weather is an important factor for your trip to Ontario, use this chart to help with planning. For those seeking warmer temperatures, August is the ideal time of year to visit, when temperatures reach an average of 78.8 F. Travelers looking to avoid the cold should look outside of December, when temperatures are typically at their lowest (around 53.6 F).
Reviews of airlines servicing Ontario
Get insights into the airlines that provide service to Ontario. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Ontario. Reviews last updated April 4, 2025.
Peruse reviews from past customers who have flown with Alaska Airlines, Southwest and Delta from St. Louis to Ontario to help guide your decision. In addition to providing an overall rating, users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Entertainment
Boarding
Overall
Crew
Food
Comfort
Reviews
Seleste,Dec 2024
FAT - SAN
Entertainment
Boarding
Overall
Crew
Food
Comfort
Reviews
Seleste,Dec 2024
FAT - SAN
Entertainment
Boarding
Overall
Crew
Food
Comfort
Reviews
Seleste,Dec 2024
FAT - SAN
Entertainment
Boarding
Overall
Crew
Food
Comfort
Reviews
Seleste,Dec 2024
FAT - SAN
Entertainment
Boarding
Overall
Crew
Food
Comfort
Reviews
Seleste,Dec 2024
FAT - SAN
Entertainment
Boarding
Overall
Crew
Food
Comfort
Reviews
Seleste,Dec 2024
FAT - SAN
Related info for your journey
Find useful and relevant information for your journey from St. Louis to Ontario. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.
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Alternative routes for St. Louis to Ontario
See prices for flight routes from nearby airports that may be better suited for you.
Top 5 airlines flying from St. Louis to Ontario
Discover the top 5 airlines that operate flights from St. Louis to Ontario. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated April 4, 2025.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$126 | Average$218 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$181 | Average$362 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$281 | Average$427 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$326 | Average$416 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$341 | Average$403 | FlexibilityNo cancel fee | On-time63% |