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Ontario

$84+ Cheap flights from Illinois to Ontario (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 5/5. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — ONT
Apr 29 — May 61
Tue 4/29
Tue 5/6
1 adult, Economy
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Cheap flight deals from Illinois to Ontario

Keep the following information in mind while searching for Illinois to Ontario flight deals. Data was last updated April 24, 2025.

Most accurate provider

Mytrip
3 stars

Most trusted provider

Mytrip
3 stars

Round-trip from

$178
(Frontier)

One-way from

$84
(Trip.com)

Popular in

December

Cheapest in

September

Average price

$288

Good round-trip deal

$264 or less

Good one-way deal

$113 or less
Provider with most accurate pricing for Chicago (CHI)-Los Angeles flight deals.
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From Illinois to Ontario
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One-way flight from Illinois to Ontario
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Highest demand for flights based on searches. 7% potential increase in price ($24 potential increase over avg. RT price).
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Cheapest flight prices on average. 2% potential price decrease ($8 potential savings vs. average RT price).
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Average for round-trip flights in April 2025
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Price to beat on a round-trip flight from Illinois to Ontario.
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Price to beat on a one-way flight from Illinois to Ontario.
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Find flight deals from Illinois to Ontario

Cheapest flights from Illinois to Ontario
Explore the most affordable flight options available from Illinois to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on April 24, 2025.

This Frontier deal was found by Cheapflights users on 4/23. 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.
Sat 4/266:58 pmSTL - ONT
1 stop7h 01mFrontier
Tue 4/2912:59 amONT - STL
1 stop7h 02mFrontier
Deal found 4/23$178
This Frontier deal was found by Cheapflights users on 4/23. 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.
Mon 5/58:40 amORD - ONT
1 stop11h 07mFrontier
Fri 5/92:28 pmONT - ORD
1 stop12h 42mFrontier
Deal found 4/23$218
This Booking.com deal was found by Cheapflights users on 4/23. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/88:03 pmMDW - ONT
1 stop5h 56mFrontier
Wed 5/1411:58 pmONT - MDW
1 stop17h 10mFrontier
Deal found 4/23$218
This United Airlines deal was found by Cheapflights users on 4/23. 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.
Wed 6/117:55 pmORD - ONT
Nonstop4h 31mUnited Airlines
Sun 6/157:00 amONT - ORD
Nonstop4h 03mUnited Airlines
Deal found 4/23$227
This Southwest deal was found by Cheapflights users on 4/23. 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.
Wed 6/118:05 pmMDW - ONT
Nonstop4h 10mSouthwest
Sun 6/155:00 amONT - MDW
Nonstop3h 50mSouthwest
Deal found 4/23$227
This American Airlines deal was found by Cheapflights users on 4/22. 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.
Sat 6/72:40 pmORD - ONT
1 stop6h 21mAmerican Airlines
Fri 6/1312:59 amONT - ORD
1 stop7h 11mAmerican Airlines
Deal found 4/22$246
This Delta deal was found by Cheapflights users on 4/23. 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.
Sat 5/244:30 pmORD - ONT
1 stop7h 46mDelta
Thu 6/121:15 pmONT - ORD
1 stop6h 54mDelta
Deal found 4/23$257
This Delta deal was found by Cheapflights users on 4/22. 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.
Sat 5/316:00 amMDW - ONT
1 stop7h 08mDelta
Sat 6/712:18 pmONT - MDW
1 stop6h 55mDelta
Deal found 4/22$257
This Trip.com deal was found by Cheapflights users on 4/22. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 5/59:55 pmSTL - ONT
1 stop16h 13mMultiple Airlines
Fri 5/910:52 amONT - STL
2 stops20h 23mMultiple Airlines
Deal found 4/22$262
This Alaska Airlines deal was found by Cheapflights users on 4/23. 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.
Tue 6/36:00 amORD - ONT
1 stop11h 50mAlaska Airlines
Thu 6/57:30 amONT - ORD
1 stop14h 26mAlaska Airlines
Deal found 4/23$266
This Hawaiian Airlines deal was found by Cheapflights users on 4/23. 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 Hawaiian Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/186:24 amORD - ONT
1 stop9h 42mHawaiian Airlines
Sun 9/217:17 pmONT - ORD
1 stop8h 23mHawaiian Airlines
Deal found 4/23$286
This Expedia deal was found by Cheapflights users on 4/23. 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.
Wed 5/149:00 amORD - ONT
1 stop8h 32mMultiple Airlines
Fri 5/1612:16 pmONT - ORD
1 stop9h 25mMultiple Airlines
Deal found 4/23$287

Cheapflights Fare Finder

Customize your flight search to find flights from Illinois 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 24, 2025.
Use the filters below to find and compare flights from Illinois to Ontario that are best for you.

Fly from

Illinois

Fly to

Ontario

Route

Depart

Return

Price

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Sat 4/26

6:58 pm-11:59 pm

1 stop7h 01m

Ontario

Tue 4/29

12:59 am-10:01 am

1 stop7h 02m

$178

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Mon 5/5

8:40 am-5:47 pm

1 stop11h 07m

Ontario

Fri 5/9

2:28 pm-5:10 am

1 stop12h 42m

$218

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Thu 5/8

8:03 pm-11:59 pm

1 stop5h 56m

Ontario

Wed 5/14

11:58 pm-7:08 pm

1 stop17h 10m

$218

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Wed 6/11

7:55 pm-10:26 pm

Nonstop4h 31m

Ontario

Sun 6/15

7:00 am-1:03 pm

Nonstop4h 03m

$227

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Wed 6/11

8:05 pm-10:15 pm

Nonstop4h 10m

Ontario

Sun 6/15

5:00 am-10:50 am

Nonstop3h 50m

$227

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Sat 6/7

2:40 pm-7:01 pm

1 stop6h 21m

Ontario

Fri 6/13

12:59 am-10:10 am

1 stop7h 11m

$246

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Sat 5/24

4:30 pm-10:16 pm

1 stop7h 46m

Ontario

Thu 6/12

1:15 pm-10:09 pm

1 stop6h 54m

$257

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Sat 5/31

6:00 am-11:08 am

1 stop7h 08m

Ontario

Sat 6/7

12:18 pm-9:13 pm

1 stop6h 55m

$257

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Mon 5/5

9:55 pm-12:08 pm

1 stop16h 13m

Ontario

Fri 5/9

10:52 am-9:15 am

2 stops20h 23m

$262

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Tue 6/3

6:00 am-3:50 pm

1 stop11h 50m

Ontario

Thu 6/5

7:30 am-11:56 pm

1 stop14h 26m

$266

Flights are sorted by cheapest round-trip flights first.

Deals found on 4/22

Showing 1-10 of 52 results
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Best time to book a flight from Illinois to Ontario

Have a flexible travel schedule? Discover the best time to fly to Ontario from Illinois with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from Illinois to Ontario

What is the cheapest month to book a flight from Illinois to Ontario?

Currently, August is the cheapest month in which you can book a flight from Illinois to Ontario (average of $246). Flying from Illinois 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 IL to ONT?

Find hourly flight availability from Illinois 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 24, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Illinois to Ontario as you normally would.

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 24, 2025.
Get a feel of what it's like to fly with Alaska Airlines, Southwest and Delta from Illinois to Ontario by reading reviews from past customers. In addition to providing an overall rating, users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
9,918 reviews

Overall

8.0

Boarding

8.2

Comfort

7.9

Crew

8.5

Entertainment

7.1

Food

7.1

Reviews

1 / 20
4.0
Okay

Anonymous,Apr 2025

LAS - STS

flight was delayed both ways even tho the weather was clear >
Alaska Airlines
8.0
Very good
9,918 reviews
Alaska Airlines
8.0
Very good
9,918 reviews

Overall

8.0

Boarding

8.2

Comfort

7.9

Crew

8.5

Entertainment

7.1

Food

7.1

Reviews

1 / 20
4.0
Okay

Anonymous,Apr 2025

LAS - STS

flight was delayed both ways even tho the weather was clear >
Southwest
8.0
Very good
4,286 reviews
Alaska Airlines
8.0
Very good
9,918 reviews

Overall

8.0

Boarding

8.2

Comfort

7.9

Crew

8.5

Entertainment

7.1

Food

7.1

Reviews

1 / 20
4.0
Okay

Anonymous,Apr 2025

LAS - STS

flight was delayed both ways even tho the weather was clear >
Delta
8.0
Very good
7,920 reviews
Alaska Airlines
8.0
Very good
9,918 reviews

Overall

8.0

Boarding

8.2

Comfort

7.9

Crew

8.5

Entertainment

7.1

Food

7.1

Reviews

1 / 20
4.0
Okay

Anonymous,Apr 2025

LAS - STS

flight was delayed both ways even tho the weather was clear >
Hawaiian Airlines
7.9
Good
2,393 reviews
Alaska Airlines
8.0
Very good
9,918 reviews

Overall

8.0

Boarding

8.2

Comfort

7.9

Crew

8.5

Entertainment

7.1

Food

7.1

Reviews

1 / 20
4.0
Okay

Anonymous,Apr 2025

LAS - STS

flight was delayed both ways even tho the weather was clear >
United Airlines
7.4
Good
8,685 reviews
Alaska Airlines
8.0
Very good
9,918 reviews

Overall

8.0

Boarding

8.2

Comfort

7.9

Crew

8.5

Entertainment

7.1

Food

7.1

Reviews

1 / 20
4.0
Okay

Anonymous,Apr 2025

LAS - STS

flight was delayed both ways even tho the weather was clear >

Related info for your journey

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

  • What airport do you fly into for flights to Ontario from Illinois?

    Located just 3.1 mi from the city center, Ontario (ONT) is the airport most travelers will use when flying to Ontario from Illinois.

  • What are the cheapest airlines to fly from Illinois to Ontario one-way?

    $84 is the cheapest one-way deal found within the past few days, from Frontier. You may also be able to find cheap deals on United Airlines and Southwest, with prices starting from $114 and $114, respectively.

  • What are the most popular routes from Illinois to Ontario?

    When deciding which route to take from Illinois to Ontario consider Chicago O'Hare Intl - Ontario, Chicago Midway - Ontario or Lambert-St Louis - Ontario as they are the most popular.

  • What are the cheapest flights from Illinois to Ontario?

    The cheapest flight price from Illinois to Ontario is $113. On average you can expect to pay $238. The most popular route, (Chicago O'Hare Intl - Ontario), can usually be booked for $201.

  • Can I find deals for flights from Illinois to Ontario that include hotel bookings?

    Yes. In addition to deals on Illinois to Ontario flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Illinois to Ontario?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Illinois to Ontario.

  • Can I find deals for business class flights from Illinois to Ontario?

    Yes. Cheapflights offers flight deals from Illinois to Ontario by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Illinois to Ontario?

    Currently, August is the cheapest month in which you can book a flight from Illinois to Ontario (average of $246). Flying from Illinois 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.

See more FAQs

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Alternative routes for Illinois to Ontario

See prices for flight routes from nearby airports that may be better suited for you.
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Top 5 airlines flying from Illinois to Ontario

Discover the top 5 airlines that operate flights from Illinois 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 24, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$123Average$197FlexibilityNo cancel feeOn-time62%
American AirlinesCheapest$204Average$575FlexibilityNo cancel feeOn-time71%
DeltaCheapest$246Average$450FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$246Average$410FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$256Average$479FlexibilityNo cancel feeOn-time63%

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