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$102+ Cheap flights from Ontario (ONT) to Illinois

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 4/12. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — ORD
abr. 2 — abr. 91
mié. 4/2
mié. 4/9
1 adult, Economy
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Cheap flight deals from Ontario to Illinois

Keep the following information in mind while searching for Ontario to Illinois flight deals. Data was last updated marzo 28, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$227
(United Airlines)

One-way from

$102
(Trip.com)

Popular in

March

Cheapest in

February

Average price

$354

Good round-trip deal

$317 or less

Good one-way deal

$158 or less
Provider with most accurate pricing for Los Angeles-Chicago (CHI) flight deals.
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From Ontario to Illinois
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One-way flight from Ontario to Illinois
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High demand for flights, 1% potential price rise
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Cheapest flight prices on average. 1% potential price decrease ($5 potential savings vs. average RT price).
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Average for round-trip flights in March 2025
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Price to beat on a round-trip flight from Ontario to Illinois.
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Price to beat on a one-way flight from Ontario to Illinois.
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Find flight deals from Ontario to Illinois

Cheapest flights from Ontario to Illinois
Explore the most affordable flight options available from Ontario to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on marzo 28, 2025.

This United Airlines deal was found by Cheapflights users on 3/27. 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.
lun. 5/267:00 amONT - ORD
Nonstop4h 03mUnited Airlines
vie. 5/307:55 pmORD - ONT
Nonstop4h 31mUnited Airlines
Deal found 3/27$227
This Cheapflightsfares deal was found by Cheapflights users on 3/27. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
vie. 4/189:41 pmONT - MDW
1 stop5h 42mFrontier
mar. 4/226:45 amMDW - ONT
1 stop6h 35mFrontier
Deal found 3/27$236
This Frontier deal was found by Cheapflights users on 3/27. 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.
vie. 4/2512:11 pmONT - ORD
1 stop9h 26mFrontier
vie. 5/25:21 pmORD - ONT
1 stop8h 38mFrontier
Deal found 3/27$238
This Southwest deal was found by Cheapflights users on 3/27. 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.
sáb. 7/196:15 amONT - ORD
1 stop6h 45mSouthwest
lun. 7/215:25 pmORD - ONT
1 stop5h 45mSouthwest
Deal found 3/27$242
This Southwest deal was found by Cheapflights users on 3/27. 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.
jue. 9/258:35 pmONT - MDW
1 stop6h 35mSouthwest
lun. 9/293:20 pmMDW - ONT
1 stop6h 25mSouthwest
Deal found 3/27$247
This Booking.com deal was found by Cheapflights users on 3/27. 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.
vie. 5/912:16 pmONT - STL
1 stop19h 43mFrontier
dom. 5/119:55 pmSTL - ONT
1 stop17h 21mFrontier
Deal found 3/27$248
This Delta deal was found by Cheapflights users on 3/27. 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.
sáb. 4/267:00 amONT - MDW
1 stop8h 59mDelta
lun. 4/284:59 pmMDW - ONT
1 stop7h 37mDelta
Deal found 3/27$257
This Delta deal was found by Cheapflights users on 3/27. 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.
sáb. 5/35:15 pmONT - ORD
1 stop5h 38mDelta
mié. 5/77:30 amORD - ONT
1 stop6h 45mDelta
Deal found 3/27$257
This Hawaiian Airlines deal was found by Cheapflights users on 3/27. 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.
sáb. 4/266:00 amONT - ORD
1 stop9h 00mHawaiian Airlines
sáb. 5/39:00 amORD - ONT
1 stop8h 32mHawaiian Airlines
Deal found 3/27$267
This Alaska Airlines deal was found by Cheapflights users on 3/27. 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.
mar. 9/237:17 pmONT - ORD
1 stop8h 23mAlaska Airlines
vie. 10/35:54 pmORD - ONT
1 stop8h 05mAlaska Airlines
Deal found 3/27$287
This American Airlines deal was found by Cheapflights users on 3/28. 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.
jue. 6/52:40 pmONT - ORD
1 stop8h 19mAmerican Airlines
dom. 6/85:00 amORD - ONT
1 stop7h 04mAmerican Airlines
Deal found 3/28$312
This American Airlines deal was found by Cheapflights users on 3/27. 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.
sáb. 5/3110:51 amONT - MLI
1 stop8h 33mAmerican Airlines
sáb. 6/73:55 pmMLI - ONT
1 stop9h 07mAmerican Airlines
Deal found 3/27$314

Cheapflights Fare Finder

Customize your flight search to find flights from Ontario to Illinois 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 marzo 28, 2025.
Use the filters below to find and compare flights from Ontario to Illinois that are best for you.

Fly from

Ontario

Fly to

Illinois

Route

Depart

Return

Price

OntarioChicago

ONT - ORD

ONTORD

Ontario

lun. 5/26

7:00 am-1:03 pm

Nonstop4h 03m

Chicago O'Hare Intl

vie. 5/30

7:55 pm-10:26 pm

Nonstop4h 31m

$227

OntarioChicago

ONT - MDW

ONTMDW

Ontario

vie. 4/18

4:25 pm-12:21 am

1 stop5h 56m

Chicago Midway

dom. 4/20

8:50 pm-7:25 am

1 stop12h 35m

$238

OntarioChicago

ONT - ORD

ONTORD

Ontario

vie. 4/25

12:11 pm-11:37 pm

1 stop9h 26m

Chicago O'Hare Intl

vie. 5/2

5:21 pm-11:59 pm

1 stop8h 38m

$238

OntarioChicago

ONT - MDW

ONTMDW

Ontario

jue. 5/29

2:55 pm-1:05 am

1 stop8h 10m

Chicago Midway

lun. 6/2

5:05 am-11:00 am

1 stop7h 55m

$247

OntarioChicago

ONT - ORD

ONTORD

Ontario

mar. 5/6

7:00 am-3:00 pm

1 stop6h 00m

Chicago O'Hare Intl

mar. 5/13

6:55 pm-11:00 pm

1 stop6h 05m

$247

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

vie. 5/9

12:16 pm-9:59 am

1 stop19h 43m

Lambert-St Louis

dom. 5/11

9:55 pm-1:16 pm

1 stop17h 21m

$248

OntarioChicago

ONT - ORD

ONTORD

Ontario

sáb. 5/3

5:15 pm-12:53 am

1 stop5h 38m

Chicago O'Hare Intl

mié. 5/7

7:30 am-12:15 pm

1 stop6h 45m

$257

OntarioChicago

ONT - ORD

ONTORD

Ontario

sáb. 4/26

6:00 am-5:00 pm

1 stop9h 00m

Chicago O'Hare Intl

sáb. 5/3

9:00 am-3:32 pm

1 stop8h 32m

$267

OntarioChicago

ONT - ORD

ONTORD

Ontario

mié. 4/30

11:46 am-11:59 pm

1 stop10h 13m

Chicago O'Hare Intl

sáb. 5/3

9:00 am-3:32 pm

1 stop8h 32m

$287

OntarioChicago

ONT - ORD

ONTORD

Ontario

jue. 6/5

2:40 pm-12:59 am

1 stop8h 19m

Chicago O'Hare Intl

dom. 6/8

5:00 am-10:04 am

1 stop7h 04m

$312

Flights are sorted by cheapest round-trip flights first.

Deals found on 3/28

Showing 1-10 of 46 results
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Best time to book a flight from Ontario to Illinois

Have a flexible travel schedule? Discover the best time to fly to Illinois from Ontario 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 Ontario to Illinois

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

Currently, August is the cheapest month in which you can book a flight from Ontario to Illinois (average of $245). Flying from Ontario to Illinois in March is currently the most expensive (average of $323). 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 ONT to IL?

Find hourly flight availability from Ontario to Illinois. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated marzo 28, 2025.

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

Rainfall in Illinois by month

Plan your trip to Illinois by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Illinois ranges from 1.7 - 4.9 inches per month. August is typically the wettest month, when rainfall can reach 4.9 in. January is typically the driest time to visit Illinois when rainfall is around 1.7 in.

Temperature in Illinois by month

Plan your trip to Illinois by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Illinois, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 73.4 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 23.0 F).

Reviews of airlines servicing Illinois

Get insights into the airlines that provide service to Illinois. 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 Illinois. Reviews last updated marzo 28, 2025.
Get a feel of what it's like to fly with Southwest, Alaska Airlines and Delta from Ontario to Illinois 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.
Southwest
8.1
Very good
4,273 reviews

Overall

8.1

Food

7.1

Boarding

8.2

Comfort

8.1

Entertainment

7.6

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Southwest
8.1
Very good
4,273 reviews
Southwest
8.1
Very good
4,273 reviews

Overall

8.1

Food

7.1

Boarding

8.2

Comfort

8.1

Entertainment

7.6

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Alaska Airlines
8.0
Very good
9,798 reviews
Southwest
8.1
Very good
4,273 reviews

Overall

8.1

Food

7.1

Boarding

8.2

Comfort

8.1

Entertainment

7.6

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Delta
8.0
Very good
7,896 reviews
Southwest
8.1
Very good
4,273 reviews

Overall

8.1

Food

7.1

Boarding

8.2

Comfort

8.1

Entertainment

7.6

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Hawaiian Airlines
7.9
Good
2,335 reviews
Southwest
8.1
Very good
4,273 reviews

Overall

8.1

Food

7.1

Boarding

8.2

Comfort

8.1

Entertainment

7.6

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
United Airlines
7.4
Good
8,603 reviews
Southwest
8.1
Very good
4,273 reviews

Overall

8.1

Food

7.1

Boarding

8.2

Comfort

8.1

Entertainment

7.6

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.

Related info for your journey

Find useful and relevant information for your journey from Ontario to Illinois. 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 from for flights from Ontario to Illinois?

    Ontario (ONT), located 3.1 mi from the city center, is the airport you fly out of when you book flights from Ontario to Illinois.

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

    $102 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 $119, respectively.

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

    The most popular flight routes from Ontario to Illinois are Ontario - Chicago O'Hare Intl, Ontario - Chicago Midway and Ontario - Lambert-St Louis.

  • What are the cheapest flights from Ontario to Illinois?

    While on average a flight from Ontario to Illinois is generally $669, our data shows the cheapest flight currently is $113. When looking at the most popular route, (Ontario - Chicago O'Hare Intl), you can expect to pay $227 for that flight.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from Ontario to Illinois 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 Ontario to Illinois?

    Currently, August is the cheapest month in which you can book a flight from Ontario to Illinois (average of $245). Flying from Ontario to Illinois in March is currently the most expensive (average of $323). 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 Ontario to Illinois

See prices for flight routes from nearby airports that may be better suited for you.
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Top 7 airlines flying from Ontario to Illinois

Discover the top 7 airlines that operate flights from Ontario to Illinois. 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 marzo 28, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$74Average$197FlexibilityNo cancel feeOn-time65%
FrontierCheapest$108Average$209FlexibilityNo cancel feeOn-time62%
Alaska AirlinesCheapest$161Average$438FlexibilityNo cancel feeOn-time75%
DeltaCheapest$241Average$396FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$246Average$482FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$246Average$511FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$262Average$470FlexibilityNo cancel feeOn-time63%
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