Cheap flights from Ontario to St. Louis (ONT - STL) from $60

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 3/8. 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.
ONT — STL
Mar 2 — Mar 91

The best prices from Ontario to Lambert-St Louis are usually found in November or October, booked 60 days in advance, depart on a Saturday or Friday and return on a Thursday

Cheap flight deals from Ontario to St. Louis

Discover tips and strategies to find the most affordable flight options for your journey from Ontario (ONT) to St. Louis (STL). 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 February 26, 2024.

Popular in

June

Cheapest in

November

Round-trip from

$323

One-way from

$60
High demand for flights, 30% potential price rise
Best time to find cheap flights, 49% potential price drop
From Ontario to Lambert-St Louis
One-way flight from Ontario to Lambert-St Louis

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

Leaving on a Friday is a viable option for saving on travel. Heavily demanded days of the week can typically drive up the prices you see. Booking your travel for a less competitive day can save up to 93% on the overall cost on flights from Ontario to St. Louis.

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

Users have found that booking a flight from Ontario to St. Louis at least 53 days early can save you up to 106% on average compared to booking a flight this week. If booking 53 days before your flight isn’t an option for you, users have found flights from Ontario to St. Louis for as little as $566 when booking for a departure date within the next two weeks. You can also check prices now. Some users have found airline tickets as low as $746 for flights departing within the next 3 days.

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

The best pricing can be found in the month of February. Prices to St. Louis from Ontario average $454. You can even find prices in February for less than $454, as users have found deals to St. Louis from as low as $258. The month of December appears to be one of the more expensive times to travel to St. Louis from Ontario. Flying in the targeted month can save you up to 10%.

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

A simple way to save on the total cost of your ticket is to fly from Ontario to St. Louis in the morning. If you’re flexible enough to do this you can expect to save up to 14% on your trip compared to booking a flight at noon.

Cheap Frontier flights from Ontario to St. Louis

Explore cheap flight options specifically provided by Frontier for the route between Ontario and St. Louis. Find affordable fares and compare prices with other airlines to secure the best deal for your journey. Over the last 7 days, Cheapflights users made 3,409,476 searches. Data last updated February 26, 2024.
Peruse some of the lowest-priced Frontier flights we've found from Ontario to St. Louis. Come back soon if you're not finding the exact deal you're looking for.
Tue 4/97:27 amONT - STL
1 stop11h 47mFrontier
Wed 4/108:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/25$106
Mon 4/812:59 amONT - STL
1 stop18h 15mFrontier
Wed 4/108:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/26$113
Sun 4/712:59 amONT - STL
1 stop7h 13mFrontier
Wed 4/108:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/26$114
Mon 4/812:59 amONT - STL
1 stop18h 15mFrontier
Wed 4/108:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/25$116
Tue 4/97:27 amONT - STL
1 stop11h 47mFrontier
Sat 4/2712:39 pmSTL - ONT
1 stop6h 20mFrontier
Deal found 2/25$120
Wed 4/2412:59 amONT - STL
1 stop7h 39mFrontier
Mon 4/298:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/26$122
Thu 5/27:16 amONT - STL
1 stop24h 31mFrontier
Mon 5/68:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/25$124
Mon 4/812:59 amONT - STL
1 stop18h 15mFrontier
Sat 4/2012:59 pmSTL - ONT
1 stop6h 00mFrontier
Deal found 2/26$127
Sun 4/712:59 amONT - STL
1 stop7h 13mFrontier
Mon 4/228:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/25$128

Cheap Alaska Airlines flights from Ontario to St. Louis

Explore cheap flight options specifically provided by Alaska Airlines for the route between Ontario and St. Louis. Find affordable fares and compare prices with other airlines to secure the best deal for your journey. Over the last 7 days, Cheapflights users made 3,409,476 searches. Data last updated February 26, 2024.
Browse through some of the cheapest Alaska Airlines flights traveling from Ontario to St. Louis. Deals frequently update to provide users with more options.
Thu 4/257:00 amONT - STL
2 stops14h 59mAlaska Airlines
Sat 4/277:00 amSTL - ONT
1 stop28h 33mAlaska Airlines
Deal found 2/25$422
Tue 4/307:00 amONT - STL
2 stops14h 59mAlaska Airlines
Fri 5/37:00 amSTL - ONT
1 stop10h 46mAlaska Airlines
Deal found 2/26$445
Thu 4/257:00 amONT - STL
2 stops14h 59mAlaska Airlines
Wed 5/12:35 pmSTL - ONT
1 stop8h 53mAlaska Airlines
Deal found 2/24$457
Tue 3/511:45 amONT - STL
2 stops23h 36mAlaska Airlines
Thu 3/72:21 pmSTL - ONT
1 stop10h 38mAlaska Airlines
Deal found 2/26$850
Wed 3/66:00 amONT - STL
2 stops11h 22mAlaska Airlines
Sun 3/107:00 amSTL - ONT
1 stop18h 29mAlaska Airlines
Deal found 2/25$957

Cheap Ontario to St. Louis flights in February & March 2024

Find cheap flight options from Ontario to St. Louis specifically for the months of February and March 2024. Explore affordable fares based on user searches. Over the last 7 days, Cheapflights users made 3,409,476 searches. Prices were last updated on February 26, 2024.
These are some of the most attractive deals on flights from Ontario to St. Louis in 2024. More deals are always being added, so be sure to check back regularly.
Fri 3/812:59 amONT - STL
1 stop7h 43mFrontier
Sat 3/167:04 pmSTL - ONT
1 stop13h 33mFrontier
Deal found 2/25$144
Wed 3/68:18 pmONT - STL
1 stop12h 05mFrontier
Mon 3/118:45 pmSTL - ONT
1 stop11h 52mFrontier
Deal found 2/25$148
Tue 3/56:00 amONT - STL
1 stop25h 00mFrontier
Thu 3/711:15 pmSTL - ONT
1 stop26h 54mFrontier
Deal found 2/26$154
Mon 3/2512:59 amONT - STL
1 stop18h 15mFrontier
Tue 4/210:04 pmSTL - ONT
1 stop10h 33mFrontier
Deal found 2/25$158
Sat 3/169:37 pmONT - STL
1 stop10h 46mFrontier
Tue 3/1910:04 pmSTL - ONT
1 stop10h 33mFrontier
Deal found 2/24$160
Mon 3/1112:59 amONT - STL
1 stop18h 15mFrontier
Sat 3/167:04 pmSTL - ONT
1 stop13h 33mFrontier
Deal found 2/25$165
Fri 3/2910:45 pmONT - STL
1 stop9h 38mFrontier
Mon 4/157:51 pmSTL - ONT
1 stop13h 12mFrontier
Deal found 2/25$167
Sun 3/1012:59 amONT - STL
1 stop7h 13mFrontier
Wed 3/138:45 pmSTL - ONT
1 stop11h 52mFrontier
Deal found 2/26$168
Thu 3/79:14 pmONT - STL
1 stop11h 09mFrontier
Sat 3/167:04 pmSTL - ONT
1 stop13h 33mFrontier
Deal found 2/25$172

Ontario to St. Louis 2024 flight deals

Discover exclusive flight deals for travel between Ontario and St. Louis in 2024. Find excellent offers based on user searches. Over the last 7 days, Cheapflights users made 3,409,476 searches. Data last updated February 26, 2024.
These are some of the most attractive deals on flights from Ontario to St. Louis in 2024. More deals are always being added, so be sure to check back regularly.
Tue 4/97:27 amONT - STL
1 stop11h 47mFrontier
Wed 4/108:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/25$106
Mon 4/812:59 amONT - STL
1 stop18h 15mFrontier
Wed 4/108:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/26$113
Sun 4/712:59 amONT - STL
1 stop7h 13mFrontier
Wed 4/108:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/26$114
Mon 4/812:59 amONT - STL
1 stop18h 15mFrontier
Wed 4/108:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/25$116
Tue 4/97:27 amONT - STL
1 stop11h 47mFrontier
Sat 4/2712:39 pmSTL - ONT
1 stop6h 20mFrontier
Deal found 2/25$120
Wed 4/2412:59 amONT - STL
1 stop7h 39mFrontier
Mon 4/298:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/26$122
Thu 5/27:16 amONT - STL
1 stop24h 31mFrontier
Mon 5/68:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/25$124
Mon 4/812:59 amONT - STL
1 stop18h 15mFrontier
Sat 4/2012:59 pmSTL - ONT
1 stop6h 00mFrontier
Deal found 2/26$127
Sun 4/712:59 amONT - STL
1 stop7h 13mFrontier
Mon 4/228:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 2/25$128

Ontario to St. Louis flights leaving soon

Find last-minute flight options from Ontario to St. Louis for spontaneous travel. Discover available flights and compare prices based on user searches. Secure great deals and offers for spontaneous trips with quick booking options. Over the last 7 days, Cheapflights users made 3,409,476 searches. Data last updated February 26, 2024.
Have a look at some of the flights available from Ontario to St. Louis departing last-minute. Tip: verify your flight details before completing your reservation.
Wed 3/68:18 pmONT - STL
1 stop12h 05mFrontier
Mon 3/118:45 pmSTL - ONT
1 stop11h 52mFrontier
Deal found 2/25$148
Tue 3/56:00 amONT - STL
1 stop25h 00mFrontier
Thu 3/711:15 pmSTL - ONT
1 stop26h 54mFrontier
Deal found 2/26$154
Thu 3/79:14 pmONT - STL
1 stop11h 09mFrontier
Sat 3/167:04 pmSTL - ONT
1 stop13h 33mFrontier
Deal found 2/25$172
Thu 3/79:14 pmONT - STL
1 stop11h 09mFrontier
Mon 3/118:45 pmSTL - ONT
1 stop11h 52mFrontier
Deal found 2/26$176
Thu 3/79:14 pmONT - STL
1 stop11h 09mFrontier
Mon 3/118:45 pmSTL - ONT
1 stop11h 52mFrontier
Deal found 2/25$178
Sun 3/39:31 pmONT - STL
1 stop11h 42mFrontier
Wed 3/68:14 pmSTL - ONT
1 stop12h 23mFrontier
Deal found 2/25$199
Tue 3/55:19 pmONT - STL
1 stop13h 41mFrontier
Sun 3/107:37 pmSTL - ONT
1 stop14h 13mFrontier
Deal found 2/25$208
Tue 3/512:53 pmONT - STL
2 stops18h 07mFrontier
Sun 3/107:37 pmSTL - ONT
1 stop14h 13mFrontier
Deal found 2/25$214
Wed 3/68:18 pmONT - STL
1 stop12h 05mFrontier
Mon 3/118:45 pmSTL - ONT
2 stops20h 21mFrontier
Deal found 2/25$219

One-way flights to St. Louis from Ontario

Search for one-way flight options from Ontario to St. Louis. Find affordable one-way fares based on user searches. Compare prices and availability to plan your one-way journey according to your preferred dates and budget. Over the last 7 days, Cheapflights users made 3,409,476 searches. Data last updated February 26, 2024.
Users in need of a one-way flight from Ontario to St. Louis can choose from these deals. Users in need of a round-trip flight from Ontario to St. Louis instead should update the search form at the top of page.
Fri 3/812:59 amONT - STL
1 stop7h 43mFrontier
Deal found 2/26$60
Wed 3/68:18 pmONT - STL
1 stop12h 05mFrontier
Deal found 2/25$66
Sat 3/97:29 pmONT - STL
1 stop11h 54mFrontier
Deal found 2/25$70
Wed 5/1512:49 amONT - STL
1 stop12h 04mFrontier
Deal found 2/25$74
Sun 4/145:40 pmONT - STL
1 stop14h 38mFrontier
Deal found 2/25$79
Tue 3/2612:59 amONT - STL
1 stop7h 13mFrontier
Deal found 2/25$80
Tue 3/2612:59 amONT - STL
1 stop7h 13mFrontier
Deal found 2/26$82
Tue 3/1210:08 pmONT - STL
1 stop10h 15mFrontier
Deal found 2/25$86
Sun 3/1012:59 amONT - STL
1 stop7h 13mFrontier
Deal found 2/25$88

Find flights from Ontario to St. Louis within your budget

Customize your flight search to find flights from Ontario to St. Louis 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 3,409,476 searches. Data last updated February 26, 2024.

Fly from

Any airport

Fly to

Any airport

Budget

$106 - $332

Route

Depart

Return

Price

OntarioLambert-St Louis

ONT - STL

ONTSTL

Ontario

Tue 4/9

1 stop11h 47m

Lambert-St Louis

Wed 4/10

1 stop5h 55m

$106

OntarioLambert-St Louis

ONT - STL

ONTSTL

Ontario

Mon 4/8

1 stop18h 15m

Lambert-St Louis

Wed 4/10

1 stop5h 55m

$113

OntarioLambert-St Louis

ONT - STL

ONTSTL

Ontario

Sun 4/7

1 stop7h 13m

Lambert-St Louis

Wed 4/10

1 stop5h 55m

$114

OntarioLambert-St Louis

ONT - STL

ONTSTL

Ontario

Mon 4/8

1 stop18h 15m

Lambert-St Louis

Wed 4/10

1 stop5h 55m

$116

OntarioLambert-St Louis

ONT - STL

ONTSTL

Ontario

Tue 4/9

1 stop11h 47m

Lambert-St Louis

Sat 4/27

1 stop6h 20m

$120

OntarioLambert-St Louis

ONT - STL

ONTSTL

Ontario

Wed 4/24

1 stop7h 39m

Lambert-St Louis

Mon 4/29

1 stop5h 55m

$122

OntarioLambert-St Louis

ONT - STL

ONTSTL

Ontario

Tue 3/12

1 stop11h 47m

Lambert-St Louis

Sat 3/16

2 stops18h 48m

$282

OntarioLambert-St Louis

ONT - STL

ONTSTL

Ontario

Tue 5/14

2 stops8h 06m

Lambert-St Louis

Tue 5/21

1 stop6h 21m

$303

OntarioLambert-St Louis

ONT - STL

ONTSTL

Ontario

Thu 4/25

2 stops11h 20m

Lambert-St Louis

Mon 4/29

2 stops12h 46m

$332

Flights are sorted by cheapest first

Deals found on 2/25

When is the best time to book a flight from Ontario to St. Louis?

Use this chart to determine the optimal time to book a round-trip flight from Ontario to St. Louis. Price data was last updated on January 28, 2024.
The best time to book flights from Ontario to St. Louis is 60 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.
Search Deals

When is the cheapest time to fly from Ontario to St. Louis?

Use this chart to determine the cheapest time to fly round-trip from Ontario to St. Louis. Price data was last updated on February 25, 2024.
Morning
Noon
Afternoon
Evening
All times are departure.
Travelers seeking maximum savings on their Ontario to St. Louis flight should consider departing on Saturday afternoons when fares are most often at their lowest. Sunday at noon flights should be avoided if possible as fares are typically the most expensive at this time.
Search Deals

Average price of flights to St. Louis by month

Plan your trip from Ontario to St. Louis by taking into account the cheapest months to travel. The average price of a one-way flight from Ontario to St. Louis is currently $76 while a round-trip flight costs $179. Price data was last updated on February 18, 2024.

Currently, October is the cheapest month in which you can book a flight from Ontario to St. Louis (average of $323). Flying from Ontario to St. Louis in June is currently the most expensive (average of $389). 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.

January

$326

February

$330

March

$346

April

$361

May

$361

June

$389

July

$383

August

$338

September

$324

October

$323

November

$335

December

$323

Temperature and rainfall in St. Louis by month

Plan your trip to St. Louis by taking into account the average temperature and rainfall totals by month.

STL

Temperature

32 - 80.6 °F

Reviews of airlines servicing St. Louis

Get insights into the airlines that provide service to St. Louis. 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 St. Louis. Reviews last updated February 26, 2024.
Read through reviews of airlines operating flights from Ontario to St. Louis, such as Frontier, Alaska Airlines and American Airlines. In addition to providing an overall rating, users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
8.1
Very good
9,254 reviews

Boarding

8.2

Crew

8.6

Comfort

7.9

Entertainment

7.4

Food

7.4

Overall

8.1

Reviews

1 / 10

It wasn't nice I was close to choked with with very little and very dry snak they didn't offer water till and hr after

8.1
Very good
9,254 reviews
8.1
Very good
9,254 reviews

Boarding

8.2

Crew

8.6

Comfort

7.9

Entertainment

7.4

Food

7.4

Overall

8.1

Reviews

1 / 10

It wasn't nice I was close to choked with with very little and very dry snak they didn't offer water till and hr after

8.1
Very good
11,853 reviews
8.1
Very good
9,254 reviews

Boarding

8.2

Crew

8.6

Comfort

7.9

Entertainment

7.4

Food

7.4

Overall

8.1

Reviews

1 / 10

It wasn't nice I was close to choked with with very little and very dry snak they didn't offer water till and hr after

7.4
Good
11,829 reviews
8.1
Very good
9,254 reviews

Boarding

8.2

Crew

8.6

Comfort

7.9

Entertainment

7.4

Food

7.4

Overall

8.1

Reviews

1 / 10

It wasn't nice I was close to choked with with very little and very dry snak they didn't offer water till and hr after

7.3
Good
15,591 reviews
8.1
Very good
9,254 reviews

Boarding

8.2

Crew

8.6

Comfort

7.9

Entertainment

7.4

Food

7.4

Overall

8.1

Reviews

1 / 10

It wasn't nice I was close to choked with with very little and very dry snak they didn't offer water till and hr after

6.4
Okay
4,483 reviews
8.1
Very good
9,254 reviews

Boarding

8.2

Crew

8.6

Comfort

7.9

Entertainment

7.4

Food

7.4

Overall

8.1

Reviews

1 / 10

It wasn't nice I was close to choked with with very little and very dry snak they didn't offer water till and hr after

Related info for your journey

Find useful and relevant information for your journey from Ontario to St. Louis. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

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

Yes, there are multiple flights from Ontario to St. Louis for under $200. The cheapest flight booked recently is on Frontier for just $106, but on average you can expect to pay $129.

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

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

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

Flying on Frontier is currently your cheapest option to St. Louis, with prices starting at $106. Frontier is priced at 72% lower than the current average price of a flight leaving 3 months from now.

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

What does ONT to STL mean?

These are just IATA (International Air Transport Association) codes. They are used in aviation to identify and differentiate airports. That’s why a Ontario Airport to Lambert-St Louis Airport flight would often be abbreviated as a ONT to STL flight.

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Ontario to St. Louis
See prices for flight routes from nearby airports that may be better suited for you.

Top 4 airlines flying from Ontario to St. Louis

Discover the top 4 airlines that operate flights from Ontario to St. Louis. 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 3,409,476 searches. Data last updated February 26, 2024.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$127Average$244FlexibilityNo cancel feeOn-time62%
Search Frontier flights
American AirlinesCheapest$282Average$485FlexibilityNo cancel feeOn-time71%
Search American Airlines flights
DeltaCheapest$304Average$470FlexibilityNo cancel feeOn-timeN/A
Search Delta flights
United AirlinesCheapest$309Average$424FlexibilityNo cancel feeOn-time69%
Search United Airlines flights

Search flights from Ontario to St. Louis by cabin class

Find flights from Ontario to St. Louis, based on your preferred cabin class, be it economy, premium economy, business, or first class.

Hourly flight availability from Ontario to St. Louis

Find hourly flight availability from Ontario to St. Louis. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated February 26, 2024.
100%of flight departuresEarly morningMidnight to 6 am
0%of flight departuresMorning6 am to noon
0%of flight departuresAfternoonNoon to 6 pm
0%of flight departuresEvening6 pm to midnight
Midnight
6 AM
Noon
6 PM

Book a flight to one of these trending destinations

User searches for flights to these destinations increased 20% or more in the past 90 days compared to other destinations

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travelers can enjoy low prices and a wide availability of flights to their desired destinations.

How does Cheapflights help users find flights from Ontario to St. Louis?

Cheapflights makes it easy to find Ontario to St. Louis flights by helping our users search from 900+ travel sites for deals. We also provide you with filters for cabin, price, airline, airports, number of stops, and many more to narrow down that perfect flight.

Why should you use Cheapflights to find cheap flight tickets from Ontario to St. Louis?

Cheapflights helps you find that perfect flight to St. Louis from Ontario by searching from hundreds of airlines and agencies you know and love. We are also free to use, in case you were wondering!

Can Cheapflights find flights from Ontario to St. Louis with no change fees?

Yes, we can. To see specific flights from Ontario to St. Louis with no change fees, users can toggle flexible booking options after using the search form above to find flights.

Can Cheapflights notify me if prices for flights from Ontario to St. Louis become cheaper?

Yes, Cheapflights offers price alerts on Ontario to St. Louis flights so you can book your travel at the perfect time. Price Alerts can be enabled by clicking the bell icon next to the flight deals above and providing your email address where you want to receive the alerts.

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