Cheap flights from St. Louis to Ontario (STL - ONT) from $69

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 4/15. 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.
STL — ONT
Mar 24 — Mar 311

The best prices from Lambert-St Louis to Ontario are usually found in August or September, booked 38 days in advance, depart on a Monday or Thursday and return on a Saturday

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 March 19, 2024.

Popular in

June

Cheapest in

August

Round-trip from

$238

One-way from

$205
High demand for flights, 34% potential price rise
Best time to find cheap flights, 46% potential price drop
From Lambert-St Louis to Ontario
One-way flight from Lambert-St Louis to Ontario

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

Thursday 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.

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

Travelers have found it’s best to book a flight 58 days in advance to save up to 30% 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 58 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 $477, or $754 for flights within the next 24 hours.

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

Our data shows that January tends to be the cheapest month to fly to Ontario from St. Louis. Users have commonly found prices around $446 for the month, but tickets can be as low as $177. Due to multiple factors, prepare for potentially higher prices in March.

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 evening. By choosing this option you can save up to 58% on the cost of your flight, compared to a flight at noon.

Cheap Frontier flights from St. Louis to Ontario

Explore cheap flight options specifically provided by Frontier for the route between St. Louis and Ontario. 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 3,145,932 searches. Data last updated March 19, 2024.
Consider these cheap Frontier flights we've found departing from St. Louis to Ontario. Make sure to double check the flight details before booking.
Thu 4/2510:59 pmSTL - ONT
1 stop10h 09mFrontier
Mon 4/2910:59 pmONT - STL
1 stop9h 19mFrontier
Deal found 3/18$130
Thu 4/2511:38 amSTL - ONT
1 stop14h 18mFrontier
Sat 4/2712:59 amONT - STL
1 stop11h 30mFrontier
Deal found 3/18$131
Tue 4/167:51 pmSTL - ONT
1 stop13h 17mFrontier
Mon 4/2212:59 amONT - STL
1 stop12h 51mFrontier
Deal found 3/18$137
Wed 4/178:04 pmSTL - ONT
1 stop12h 22mFrontier
Wed 4/2410:49 pmONT - STL
1 stop9h 29mFrontier
Deal found 3/18$138
Sat 4/1312:59 pmSTL - ONT
1 stop6h 00mFrontier
Fri 4/1912:59 amONT - STL
1 stop6h 48mFrontier
Deal found 3/17$139
Tue 4/3010:59 pmSTL - ONT
1 stop10h 09mFrontier
Wed 5/110:49 pmONT - STL
1 stop9h 29mFrontier
Deal found 3/17$140
Thu 4/2510:59 pmSTL - ONT
1 stop10h 09mFrontier
Sun 4/2812:59 amONT - STL
1 stop6h 48mFrontier
Deal found 3/18$146
Thu 4/2510:59 pmSTL - ONT
1 stop10h 09mFrontier
Mon 4/2910:59 pmONT - STL
2 stops14h 51mFrontier
Deal found 3/18$151
Fri 4/125:35 pmSTL - ONT
1 stop8h 24mFrontier
Tue 4/2312:59 amONT - STL
1 stop6h 48mFrontier
Deal found 3/18$152

Cheap Delta flights from St. Louis to Ontario

Explore cheap flight options specifically provided by Delta for the route between St. Louis and Ontario. 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 3,145,932 searches. Data last updated March 19, 2024.
Have a look at some of the cheapest available Delta flights departing from St. Louis and landing in Ontario. If these deals don't fit your criteria, make sure to check back soon as new deals are always added.
Sat 5/255:30 pmSTL - ONT
1 stop6h 09mDelta
Tue 6/41:20 pmONT - STL
1 stop6h 04mDelta
Deal found 3/18$446
Tue 6/185:05 pmSTL - ONT
1 stop7h 07mDelta
Sat 6/225:00 pmONT - STL
1 stop5h 36mDelta
Deal found 3/17$456
Mon 5/276:50 pmSTL - ONT
1 stop6h 53mDelta
Sat 6/15:45 amONT - STL
1 stop5h 47mDelta
Deal found 3/18$476
Sat 4/1310:20 amSTL - ONT
2 stops13h 17mDelta
Sat 4/206:00 amONT - STL
1 stop6h 46mDelta
Deal found 3/18$493
Sat 6/155:05 pmSTL - ONT
1 stop7h 07mDelta
Sat 6/225:00 pmONT - STL
1 stop5h 36mDelta
Deal found 3/17$552
Sun 3/247:30 amSTL - ONT
1 stop6h 44mDelta
Thu 4/412:38 pmONT - STL
1 stop7h 56mDelta
Deal found 3/18$708
Fri 3/296:00 amSTL - ONT
1 stop7h 27mDelta
Fri 3/295:01 pmONT - STL
1 stop5h 43mDelta
Deal found 3/18$766
Tue 3/265:30 pmSTL - ONT
1 stop8h 16mDelta
Mon 4/15:01 pmONT - STL
1 stop5h 49mDelta
Deal found 3/18$805
Thu 3/2811:59 amSTL - ONT
1 stop6h 06mDelta
Mon 4/15:01 pmONT - STL
1 stop5h 49mDelta
Deal found 3/18$829

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

Find cheap flight options from St. Louis to Ontario specifically for the months of March and April 2024. Explore affordable fares based on user searches. Over the last 7 days, Cheapflights users made 3,145,932 searches. Prices were last updated on March 19, 2024.
Scroll through some of the best deals on flights from St. Louis to Ontario in 2024. For more flight deals, be sure to check back very soon.
Thu 4/2510:59 pmSTL - ONT
1 stop10h 09mFrontier
Mon 4/2910:59 pmONT - STL
1 stop9h 19mFrontier
Deal found 3/18$130
Thu 4/2511:38 amSTL - ONT
1 stop14h 18mFrontier
Sat 4/2712:59 amONT - STL
1 stop11h 30mFrontier
Deal found 3/18$131
Tue 4/167:51 pmSTL - ONT
1 stop13h 17mFrontier
Mon 4/2212:59 amONT - STL
1 stop12h 51mFrontier
Deal found 3/18$137
Thu 4/1110:56 pmSTL - ONT
1 stop10h 12mFrontier
Mon 4/1510:59 pmONT - STL
1 stop9h 19mFrontier
Deal found 3/19$138
Sat 4/1312:59 pmSTL - ONT
1 stop6h 00mFrontier
Fri 4/1912:59 amONT - STL
1 stop6h 48mFrontier
Deal found 3/17$139
Tue 4/3010:59 pmSTL - ONT
1 stop10h 09mFrontier
Wed 5/110:49 pmONT - STL
1 stop9h 29mFrontier
Deal found 3/17$140
Thu 4/2510:59 pmSTL - ONT
1 stop10h 09mFrontier
Sun 4/2812:59 amONT - STL
1 stop6h 48mFrontier
Deal found 3/18$146
Thu 4/1110:56 pmSTL - ONT
1 stop10h 12mFrontier
Sun 4/1412:59 amONT - STL
1 stop6h 48mFrontier
Deal found 3/19$147
Thu 4/2510:59 pmSTL - ONT
1 stop14h 46mFrontier
Mon 4/2910:59 pmONT - STL
2 stops14h 51mFrontier
Deal found 3/18$151

St. Louis to Ontario 2024 flight deals

Discover exclusive flight deals for travel between St. Louis and Ontario in 2024. Find excellent offers based on user searches. Over the last 7 days, Cheapflights users made 3,145,932 searches. Data last updated March 19, 2024.
Scroll through some of the best deals on flights from St. Louis to Ontario in 2024. For more flight deals, be sure to check back very soon.
Thu 4/2510:59 pmSTL - ONT
1 stop10h 09mFrontier
Mon 4/2910:59 pmONT - STL
1 stop9h 19mFrontier
Deal found 3/18$130
Thu 4/2511:38 amSTL - ONT
1 stop14h 18mFrontier
Sat 4/2712:59 amONT - STL
1 stop11h 30mFrontier
Deal found 3/18$131
Tue 4/167:51 pmSTL - ONT
1 stop13h 17mFrontier
Mon 4/2212:59 amONT - STL
1 stop12h 51mFrontier
Deal found 3/18$137
Thu 4/1110:56 pmSTL - ONT
1 stop10h 12mFrontier
Mon 4/1510:59 pmONT - STL
1 stop9h 19mFrontier
Deal found 3/19$138
Sat 4/1312:59 pmSTL - ONT
1 stop6h 00mFrontier
Fri 4/1912:59 amONT - STL
1 stop6h 48mFrontier
Deal found 3/17$139
Tue 4/3010:59 pmSTL - ONT
1 stop10h 09mFrontier
Wed 5/110:49 pmONT - STL
1 stop9h 29mFrontier
Deal found 3/17$140
Thu 4/2510:59 pmSTL - ONT
1 stop10h 09mFrontier
Sun 4/2812:59 amONT - STL
1 stop6h 48mFrontier
Deal found 3/18$146
Thu 4/1110:56 pmSTL - ONT
1 stop10h 12mFrontier
Sun 4/1412:59 amONT - STL
1 stop6h 48mFrontier
Deal found 3/19$147
Thu 4/2510:59 pmSTL - ONT
1 stop14h 46mFrontier
Mon 4/2910:59 pmONT - STL
2 stops14h 51mFrontier
Deal found 3/18$151

St. Louis to Ontario flights leaving soon

Find last-minute flight options from St. Louis to Ontario 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 3,145,932 searches. Data last updated March 19, 2024.
Have a look at some of the last-minute flights available departing from St. Louis to Ontario. It's wise to confirm all flight details are correct before booking.
Wed 3/277:37 pmSTL - ONT
1 stop14h 13mFrontier
Tue 4/210:08 pmONT - STL
1 stop10h 15mFrontier
Deal found 3/19$158
Tue 3/267:37 pmSTL - ONT
1 stop14h 33mFrontier
Tue 4/25:26 pmONT - STL
1 stop14h 57mFrontier
Deal found 3/19$159
Fri 3/296:18 pmSTL - ONT
1 stop15h 32mFrontier
Mon 4/89:55 pmONT - STL
1 stop10h 28mFrontier
Deal found 3/18$160
Wed 3/277:37 pmSTL - ONT
1 stop14h 13mFrontier
Tue 4/212:59 amONT - STL
1 stop7h 13mFrontier
Deal found 3/18$163
Tue 3/267:37 pmSTL - ONT
1 stop14h 33mFrontier
Tue 4/212:59 amONT - STL
1 stop7h 13mFrontier
Deal found 3/18$164
Wed 3/277:37 pmSTL - ONT
1 stop14h 13mFrontier
Mon 4/112:59 amONT - STL
1 stop18h 15mFrontier
Deal found 3/18$169
Tue 3/2610:04 pmSTL - ONT
1 stop10h 33mFrontier
Thu 4/45:26 pmONT - STL
1 stop14h 57mFrontier
Deal found 3/18$170
Tue 3/2610:04 pmSTL - ONT
1 stop10h 33mFrontier
Fri 3/2910:45 pmONT - STL
1 stop9h 38mFrontier
Deal found 3/18$178
Mon 3/257:37 pmSTL - ONT
1 stop18h 21mFrontier
Mon 4/19:55 pmONT - STL
1 stop10h 28mFrontier
Deal found 3/19$180

One-way flights to Ontario from St. Louis

Search for one-way flight options from St. Louis to Ontario. 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 3,145,932 searches. Data last updated March 19, 2024.
Users in need of a one-way flight from St. Louis to Ontario can choose from these deals. Users in need of a round-trip flight from St. Louis to Ontario instead should update the search form at the top of page.
Mon 4/158:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 3/18$69
Mon 5/68:04 pmSTL - ONT
1 stop5h 55mFrontier
Deal found 3/18$70
Sun 4/1411:21 pmSTL - ONT
1 stop9h 42mFrontier
Deal found 3/18$75
Tue 3/2610:04 pmSTL - ONT
1 stop10h 33mFrontier
Deal found 3/18$76
Thu 5/910:59 pmSTL - ONT
1 stop10h 09mFrontier
Deal found 3/18$77
Fri 5/105:35 pmSTL - ONT
1 stop8h 20mFrontier
Deal found 3/18$78
Sun 4/77:37 pmSTL - ONT
1 stop16h 31mFrontier
Deal found 3/17$79
Fri 4/265:35 pmSTL - ONT
1 stop8h 20mFrontier
Deal found 3/18$89
Wed 5/298:00 pmSTL - ONT
1 stop18h 15mFrontier
Deal found 3/18$90

Find flights from St. Louis to Ontario within your budget

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 3,145,932 searches. Data last updated March 19, 2024.

Fly from

Any airport

Fly to

Any airport

Budget

$130 - $446

Route

Depart

Return

Price

Lambert-St LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Thu 4/25

1 stop10h 09m

Ontario

Mon 4/29

1 stop9h 19m

$130

Lambert-St LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Thu 4/25

1 stop14h 18m

Ontario

Sat 4/27

1 stop11h 30m

$131

Lambert-St LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Tue 4/16

1 stop13h 17m

Ontario

Mon 4/22

1 stop12h 51m

$137

Lambert-St LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Wed 4/17

1 stop12h 22m

Ontario

Wed 4/24

1 stop9h 29m

$138

Lambert-St LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Sat 4/13

1 stop6h 00m

Ontario

Fri 4/19

1 stop6h 48m

$139

Lambert-St LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Tue 4/30

1 stop10h 09m

Ontario

Wed 5/1

1 stop9h 29m

$140

Lambert-St LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Sat 4/13

1 stop6h 12m

Ontario

Sat 4/20

1 stop5h 22m

$357

Lambert-St LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Sat 4/13

2 stops16h 52m

Ontario

Sat 4/20

1 stop15h 59m

$432

Lambert-St LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Sat 5/25

1 stop6h 09m

Ontario

Tue 6/4

1 stop6h 04m

$446

Flights are sorted by cheapest first

Deals found on 3/18

When is the best time to 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 January 28, 2024.
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 37 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.
Search Deals

When is the cheapest time 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 March 17, 2024.
Morning
Noon
Afternoon
Evening
All times are departure.
Travelers seeking maximum savings on their St. Louis to Ontario flight should consider departing on Sunday at noon when fares are most often at their lowest. Friday 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 Ontario by month

Plan your trip from St. Louis to Ontario by taking into account the cheapest months to travel. The average price of a one-way flight from St. Louis to Ontario is currently $78 while a round-trip flight costs $228. Price data was last updated on March 10, 2024.

Currently, October is the cheapest month in which you can book a flight from St. Louis to Ontario (average of $238). Flying from St. Louis to Ontario in June is currently the most expensive (average of $357). 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

$271

February

$287

March

$281

April

$306

May

$282

June

$357

July

$332

August

$288

September

$258

October

$238

November

$268

December

$271

Temperature and rainfall in Ontario by month

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

LAX

Temperature

57.2 - 73.4 °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 March 19, 2024.
Peruse reviews from past customers who have flown with Frontier, Delta and Alaska Airlines 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.
8.1
Very good
9,150 reviews

Food

7.3

Entertainment

7.4

Boarding

8.2

Crew

8.6

Comfort

7.9

Overall

8.1

Reviews

1 / 10

This is trivial however, I was in row 11B there aren’t any windows in that row. I enjoy being able to look out the window.

8.1
Very good
9,150 reviews
8.1
Very good
9,150 reviews

Food

7.3

Entertainment

7.4

Boarding

8.2

Crew

8.6

Comfort

7.9

Overall

8.1

Reviews

1 / 10

This is trivial however, I was in row 11B there aren’t any windows in that row. I enjoy being able to look out the window.

8.1
Very good
11,551 reviews
8.1
Very good
9,150 reviews

Food

7.3

Entertainment

7.4

Boarding

8.2

Crew

8.6

Comfort

7.9

Overall

8.1

Reviews

1 / 10

This is trivial however, I was in row 11B there aren’t any windows in that row. I enjoy being able to look out the window.

7.4
Good
11,602 reviews
8.1
Very good
9,150 reviews

Food

7.3

Entertainment

7.4

Boarding

8.2

Crew

8.6

Comfort

7.9

Overall

8.1

Reviews

1 / 10

This is trivial however, I was in row 11B there aren’t any windows in that row. I enjoy being able to look out the window.

7.3
Good
15,312 reviews
8.1
Very good
9,150 reviews

Food

7.3

Entertainment

7.4

Boarding

8.2

Crew

8.6

Comfort

7.9

Overall

8.1

Reviews

1 / 10

This is trivial however, I was in row 11B there aren’t any windows in that row. I enjoy being able to look out the window.

6.4
Okay
4,333 reviews
8.1
Very good
9,150 reviews

Food

7.3

Entertainment

7.4

Boarding

8.2

Crew

8.6

Comfort

7.9

Overall

8.1

Reviews

1 / 10

This is trivial however, I was in row 11B there aren’t any windows in that row. I enjoy being able to look out the window.

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.
  • 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 Frontier for just $130, but on average you can expect to pay $153.

  • 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 $130, was found to be the cheapest airline from St. Louis to Ontario.. Frontier is priced at 64% 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 $69. However, be on the lookout for offers from Alaska Airlines and United Airlines, as they are both options that can get you from St. Louis to Ontario for a low price.

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

  • What does STL to ONT mean?

    Lambert-St Louis Airport is STL and Ontario Airport is ONT. These codes are created by the International Air Transport Association (IATA) and airlines use them to identify the departing and arrival airports in the flight routes they service.

See more FAQs

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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 4 airlines flying from St. Louis to Ontario

Discover the top 4 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 3,145,932 searches. Data last updated March 19, 2024.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$130Average$227FlexibilityNo cancel feeOn-time62%
Search Frontier flights
DeltaCheapest$286Average$452FlexibilityNo cancel feeOn-timeN/A
Search Delta flights
American AirlinesCheapest$310Average$500FlexibilityNo cancel feeOn-time71%
Search American Airlines flights
United AirlinesCheapest$337Average$622FlexibilityNo cancel feeOn-time69%
Search United Airlines flights

Search flights from St. Louis to Ontario by cabin class

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

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 St. Louis to Ontario?

When you search for this flight from St. Louis to Ontario, Cheapflights searches on 900+ travel sites to save you time finding great flight deals online. Additionally, we offer filter features so you can choose a preferred cabin class or airline, see different price ranges, and much more so you can book the flight for you.

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

Cheapflights taps into our reliable network of hundreds of airlines and travel agencies to find the best deals for flights from St. Louis to Ontario for you. Better yet — we are completely free to use.

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

Certainly. Search results for flights to Ontario from St. Louis shown to you on Cheapflights can be narrowed down with different useful search filters, which includes flexible booking options.

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

Yes! Start tracking prices for St. Louis to Ontario flights today and get alerted whenever prices for these flights change. To access this feature, click the bell icon next to the flight deals above, which will prompt you for a valid email address to receive your alerts.

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