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

Know your dates, get live prices in seconds:

From
To
Depart
Return
Any month
Compare vs. Cheapflights |
From
To
Depart
Depart
Time
Anytime
From
To
Depart
Depart
Time
Anytime
From
To
Depart
Depart
Time
Anytime
From
To
Depart
Depart
Time
Anytime
From
To
Depart
Depart
Time
Anytime
From
To
Depart
Depart
Time
Anytime

We work with more than 300 partners to bring you better travel deals

The best prices from Lambert-St Louis to Ontario are usually found in September or October, booked 57 days in advance, depart on a Tuesday or Monday and return on a Wednesday

How to find the cheapest flight from
St. Louis (STL) to Ontario (ONT)

All the information you need to plan the best STL to ONT flight in 2022: compare St. Louis to Ontario flight prices with the expected peak season, weather and rainfall in Ontario.
STL - ONT
Price
$214 - $525
ONT
Temperature
53.6 - 78.8 °F
ONT
Rainfall
0.1 - 3.4 inches

Popular in

March

High demand for flights, 42% potential price rise

Cheapest in

September

Best time to find cheap flights, 30% potential price drop

Round-trip from

$214

From Lambert-St Louis to Ontario

One-way from

$154

One-way flight from Lambert-St Louis to Ontario

Flight route prices based on searches on Cheapflights within the last 3 days, monthly prices based on aggregated historical data.
What is the cheapest day to fly round-trip from St. Louis to Ontario?

Saturday flights are generally found to be more expensive for flights from St. Louis to Ontario. This shouldn’t discourage you from searching, as you can still find great deals by being flexible with your options. Use our search form to find deals on tickets to Ontario.

When is the cheapest time to fly from St. Louis to Ontario (STL - ONT)?

It’s optimal to fly from St. Louis to Ontario in the afternoon. By choosing this option you can save up to 45% on the cost of your flight, compared to a flight in the morning.

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

Travelers have found it’s best to book a flight 45 days in advance to save up to 28% compared to booking the same week of travel. As your travel date approaches, the cost of this flight route may potentially increase. While opting to book 45 days out may not be an option for all, there are still additional ways to secure a deal in the near future. You might find a flight from St. Louis to Ontario 1-2 weeks in advance for as low as $241, or $242 for flights within the next 24 hours.

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

Our data shows that October tends to be the cheapest month to fly to Ontario from St. Louis. Users have commonly found prices around $232 for the month, but tickets can be as low as $50. Due to multiple factors, prepare for potentially higher prices in June.

Cheap flights from St. Louis to Ontario in August, September 2022

The best prices found for STL to ONT flights for August, September
6 Sep - 13 Sep
$135pp
STL
Lambert-St Louis
Multiple Airlines
 
1 STOP
ONT
Ontario
ONT
Ontario
Frontier
 
1 STOP
STL
Lambert-St Louis
10 Sep - 13 Sep
$149pp
STL
Lambert-St Louis
Frontier
 
1 STOP
ONT
Ontario
ONT
Ontario
Frontier
 
1 STOP
STL
Lambert-St Louis
3 Sep - 7 Sep
$153pp
STL
Lambert-St Louis
Multiple Airlines
 
1 STOP
ONT
Ontario
ONT
Ontario
Frontier
 
1 STOP
STL
Lambert-St Louis

Lambert-St Louis to Ontario 2022 flight deals

Cheap flights to Ontario from St. Louis found for this year
6 Sep - 13 Sep
$135pp
STL
Lambert-St Louis
Multiple Airlines
 
1 STOP
ONT
Ontario
ONT
Ontario
Frontier
 
1 STOP
STL
Lambert-St Louis
10 Sep - 13 Sep
$149pp
STL
Lambert-St Louis
Frontier
 
1 STOP
ONT
Ontario
ONT
Ontario
Frontier
 
1 STOP
STL
Lambert-St Louis
3 Sep - 7 Sep
$153pp
STL
Lambert-St Louis
Multiple Airlines
 
1 STOP
ONT
Ontario
ONT
Ontario
Frontier
 
1 STOP
STL
Lambert-St Louis

Cheap Frontier flights from St. Louis to Ontario

10 Sep - 13 Sep
$149pp
STL
Lambert-St Louis
Frontier
 
1 STOP
ONT
Ontario
ONT
Ontario
Frontier
 
1 STOP
STL
Lambert-St Louis
10 Sep - 17 Sep
$160pp
STL
Lambert-St Louis
Frontier
 
1 STOP
ONT
Ontario
ONT
Ontario
Frontier
 
1 STOP
STL
Lambert-St Louis
10 Nov - 11 Nov
$161pp
STL
Lambert-St Louis
Frontier
 
1 STOP
ONT
Ontario
ONT
Ontario
Frontier
 
1 STOP
STL
Lambert-St Louis

Cheap American Airlines flights from St. Louis to Ontario

20 Aug - 29 Aug
$379pp
STL
Lambert-St Louis
American Airlines
   
2 STOPS
ONT
Ontario
ONT
Ontario
American Airlines
 
1 STOP
STL
Lambert-St Louis
18 Aug - 24 Aug
$380pp
STL
Lambert-St Louis
American Airlines
   
2 STOPS
ONT
Ontario
ONT
Ontario
American Airlines
 
1 STOP
STL
Lambert-St Louis
19 Aug - 22 Aug
$416pp
STL
Lambert-St Louis
American Airlines
 
1 STOP
ONT
Ontario
ONT
Ontario
American Airlines
 
1 STOP
STL
Lambert-St Louis

Last minute flights from St. Louis to Ontario

Late deals on round-trip flights to Ontario from St. Louis, departing today and this week
18 Aug - 24 Aug
$164pp
STL
Lambert-St Louis
Frontier
 
1 STOP
ONT
Ontario
ONT
Ontario
Frontier
 
1 STOP
STL
Lambert-St Louis
17 Aug - 16 Sep
$168pp
STL
Lambert-St Louis
Frontier
 
1 STOP
ONT
Ontario
ONT
Ontario
Frontier
 
1 STOP
STL
Lambert-St Louis
18 Aug - 21 Aug
$235pp
STL
Lambert-St Louis
Frontier
 
1 STOP
ONT
Ontario
ONT
Ontario
Frontier
 
1 STOP
STL
Lambert-St Louis

One-way flights to Ontario from St. Louis

The cheapest one-way flights from St. Louis to Ontario
8:59 am - 7:15 am
Frontier
2 Stops
24h 16m
STL - ONT
Frontier
$154
Kiwi.com
2:35 am - 8:28 am
Delta
1 Stop
7h 53m
STL - ONT
Delta
$168
Delta
8:50 am - 5:30 pm
Multiple Airlines
1 Stop
10h 40m
STL - ONT
Multiple Airlines
$171
FlightHub

Related info for your journey

Useful info, stats and facts about <span class="emphasized">St. Louis</span> to <span class="emphasized">Ontario</span> flights.

Flight FAQs

From St. Louis to Ontario

What airports do I use to fly from St. Louis to Ontario?

You will need to book a flight from Lambert-St Louis to Ontario if you want to fly from St. Louis to Ontario. At least 6 different airlines have flights from Lambert-St Louis (STL) to Ontario (ONT) on a regular basis. There is 1 flight to Ontario from the St. Louis airport per day. If you manage to book one that is nonstop, then you can expect the flight time from STL to ONT to be around 6h 04m.

Which airlines flying from Lambert-St Louis to Ontario have flexible cancellations due to COVID-19?

Some of the carriers operating flights from Lambert-St Louis to Ontario that may be offering flexible cancellation policies are American Airlines, Frontier, and Delta. Our site will let you filter for all airlines offering greater flexibility due to COVID-19.

Can I find flights from St. Louis to Ontario for under $200 on Cheapflights?

Yes, there are multiple flights from St. Louis to Ontario for under $200. The cheapest flight booked recently is on Multiple Airlines for just $135, but on average you can expect to pay $167.

Are there last-minute flights available from St. Louis to Ontario for under $200?

There are currently 20+ open flights from St. Louis to Ontario within the next 7 days for less than $200.

What is the cheapest airline to fly from St. Louis to Ontario round-trip?

Frontier, at $149, was found to be the cheapest airline from St. Louis to Ontario.. Frontier is priced at 51% lower than the current average price of a flight leaving 3 months from now.

What are the cheapest airlines to fly from St. Louis to Ontario one-way?

The cheapest airline one-way is Frontier, with whom users have recently found tickets for as low as $73. However, be on the lookout for offers from Delta and American Airlines, as they are both options that can get you from St. Louis to Ontario for a low price.

What are the cheapest flights from St. Louis to Ontario?

The cheapest flight price from St. Louis to Ontario is $22. On average you can expect to pay $498. The most popular route, (Lambert-St Louis - Ontario), can usually be booked for $135.

What are the most popular airlines that fly from St. Louis to Ontario?

Before booking your flight from St. Louis to Ontario check out the most popular airlines for this route: American Airlines, Delta or Frontier.

COVID Restrictions

View COVID Travel Restrictions for Ontario, CA

Do I need a COVID test to fly to Ontario from St. Louis?

Information is based on travel restrictions for travel to Ontario within the United States

Most visitors from Lambert-St Louis need to provide a negative COVID-19 test result and/or quarantine to enter Ontario.

COVID-19 testing requirements
Visitors from Lambert-St Louis are not required to present a negative COVID-19 PCR test or antigen result upon entering Ontario.

Quarantine requirements
Visitors from Lambert-St Louis are not required to quarantine after entering Ontario.

Do I need a test to fly back to St. Louis from Ontario?

Returning to Lambert-St Louis from Ontario

COVID-19 testing requirements
Visitors from Ontario are not required to present a negative COVID-19 PCR test or antigen result upon entering Lambert-St Louis.

Quarantine requirements
Visitors from Ontario are not required to quarantine after entering Lambert-St Louis.

Hide COVID Travel Restrictions for Ontario, CA

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 Lambert-St Louis to Ontario

The chart below displays the airlines Cheapflights users traveling from St. Louis to Ontario choose most often. Cheapest and average prices are based on aggregated data from the past 12 months.
Airline Cheapest Average Flexibility On-time COVID-19 safety
Juneyao Airlines
$17 $22 No cancel fee 66%

We couldn't confirm the COVID-19 safety measures taken by Juneyao Airlines. Please check directly on their website for additional information.

Frontier
$126 $218 No cancel fee 62%
American Airlines
$194 $515 No cancel fee 71%
United Airlines
$211 $602 No cancel fee 69%
Delta
$223 $424 No cancel fee N/A

Hourly flight availability from St. Louis to Ontario

See what time of day planes typically take off from St. Louis towards Ontario.
Early morning Midnight to 6 AM 100% of STL to ONT departures
Morning 6 AM to noon 0% of STL to ONT departures
Afternoon Noon to 6 PM 0% of STL to ONT departures
Evening 6 PM to midnight 0% of STL to ONT departures
Midnight
6 AM
Noon
6 PM
Weekly flight availability
from St. Louis to Ontario
See how many times per day planes take to the skies headed from St. Louis to Ontario.
Sunday
2 daily flights
Monday
2 daily flights
Tuesday
2 daily flights
Wednesday
2 daily flights
Thursday
2 daily flights
Friday
2 daily flights
Saturday
1 daily flight