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$104+ 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 6/8. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — ORD
may. 17 — may. 241
sáb. 5/17
sáb. 5/24
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 mayo 12, 2025.

Most accurate provider

CheapOair
3 stars

Most trusted provider

CheapOair
3 stars

Round-trip from

$221
(Trip.com)

One-way from

$104
(Cheapflightsfares)

Popular in

December

Cheapest in

February

Average price

$279

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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Highest demand for flights based on searches. 6% potential increase in price ($22 potential increase over avg. RT price).
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Cheapest flight prices on average. 1% potential price decrease ($4 potential savings vs. average RT price).
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Average for round-trip flights in May 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 mayo 12, 2025.

This Trip.com deal was found by Cheapflights users on 5/11. 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.
vie. 5/2312:59 amONT - STL
1 stop7h 10mFrontier
mar. 5/272:40 pmSTL - ONT
1 stop8h 09mFrontier
Deal found 5/11$221
This Trip.com deal was found by Cheapflights users on 5/11. 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.
vie. 5/305:21 pmONT - MDW
1 stop25h 32mFrontier
lun. 6/26:25 amMDW - ONT
1 stop7h 55mFrontier
Deal found 5/11$237
This United Airlines deal was found by Cheapflights users on 5/11. 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.
mié. 6/256:41 pmONT - ORD
1 stop8h 23mUnited Airlines
sáb. 7/127:35 pmORD - ONT
Nonstop4h 31mUnited Airlines
Deal found 5/11$237
This Gotogate deal was found by Cheapflights users on 5/11. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
vie. 8/2212:59 amONT - ORD
1 stop20h 54mFrontier
dom. 9/149:57 pmORD - ONT
1 stop15h 50mFrontier
Deal found 5/11$238
This Hawaiian Airlines deal was found by Cheapflights users on 5/12. 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.
mar. 8/2611:39 amONT - ORD
1 stop10h 20mHawaiian Airlines
sáb. 8/306:20 amORD - ONT
1 stop9h 49mHawaiian Airlines
Deal found 5/12$246
This Southwest deal was found by Cheapflights users on 5/12. 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.
vie. 7/258:05 pmONT - MDW
1 stop6h 55mSouthwest
mar. 7/295:25 pmMDW - ONT
1 stop7h 45mSouthwest
Deal found 5/12$247
This American Airlines deal was found by Cheapflights users on 5/12. 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.
mar. 7/112:55 pmONT - ORD
1 stop7h 36mAmerican Airlines
sáb. 7/121:23 pmORD - ONT
1 stop7h 30mAmerican Airlines
Deal found 5/12$247
This Delta deal was found by Cheapflights users on 5/10. 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.
mié. 7/161:15 pmONT - ORD
1 stop6h 53mDelta
sáb. 7/197:40 amORD - ONT
1 stop6h 34mDelta
Deal found 5/10$255
This Delta deal was found by Cheapflights users on 5/12. 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.
mar. 8/2610:59 pmONT - MDW
1 stop8h 52mDelta
sáb. 8/306:00 amMDW - ONT
1 stop7h 07mDelta
Deal found 5/12$257
This Alaska Airlines deal was found by Cheapflights users on 5/11. 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. 6/107:20 pmONT - ORD
1 stop8h 20mAlaska Airlines
mar. 6/1710:00 amORD - ONT
1 stop10h 04mAlaska Airlines
Deal found 5/11$266
This American Airlines deal was found by Cheapflights users on 5/11. 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. 8/212:31 pmONT - MLI
1 stop6h 51mAmerican Airlines
dom. 8/245:26 pmMLI - ONT
1 stop8h 42mAmerican Airlines
Deal found 5/11$289
This American Airlines deal was found by Cheapflights users on 5/11. 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.
lun. 7/711:59 pmONT - PIA
1 stop8h 40mAmerican Airlines
sáb. 7/124:44 pmPIA - ONT
1 stop7h 43mAmerican Airlines
Deal found 5/11$289

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 mayo 12, 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

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

vie. 5/23

12:59 am-10:09 am

1 stop7h 10m

Lambert-St Louis

mar. 5/27

2:40 pm-8:49 pm

1 stop8h 09m

$221

OntarioChicago

ONT - ORD

ONTORD

Ontario

mié. 6/25

6:41 pm-5:04 am

1 stop8h 23m

Chicago O'Hare Intl

sáb. 7/12

7:35 pm-10:06 pm

Nonstop4h 31m

$237

OntarioChicago

ONT - MDW

ONTMDW

Ontario

vie. 5/30

5:21 pm-8:53 pm

1 stop25h 32m

Chicago Midway

lun. 6/2

6:25 am-12:20 pm

1 stop7h 55m

$237

OntarioChicago

ONT - ORD

ONTORD

Ontario

vie. 8/22

12:59 am-11:53 pm

1 stop20h 54m

Chicago O'Hare Intl

dom. 9/14

9:57 pm-11:47 am

1 stop15h 50m

$238

OntarioChicago

ONT - ORD

ONTORD

Ontario

mar. 8/26

11:39 am-11:59 pm

1 stop10h 20m

Chicago O'Hare Intl

sáb. 8/30

6:20 am-2:09 pm

1 stop9h 49m

$246

OntarioChicago

ONT - MDW

ONTMDW

Ontario

vie. 7/25

8:05 pm-5:00 am

1 stop6h 55m

Chicago Midway

mar. 7/29

5:25 pm-11:10 pm

1 stop7h 45m

$247

OntarioChicago

ONT - ORD

ONTORD

Ontario

mar. 7/1

12:55 pm-10:31 pm

1 stop7h 36m

Chicago O'Hare Intl

sáb. 7/12

1:23 pm-6:53 pm

1 stop7h 30m

$247

OntarioChicago

ONT - ORD

ONTORD

Ontario

mié. 7/16

1:15 pm-10:08 pm

1 stop6h 53m

Chicago O'Hare Intl

sáb. 7/19

7:40 am-12:14 pm

1 stop6h 34m

$255

OntarioChicago

ONT - MDW

ONTMDW

Ontario

mar. 8/26

10:59 pm-9:51 am

1 stop8h 52m

Chicago Midway

sáb. 8/30

6:00 am-11:07 am

1 stop7h 07m

$257

OntarioChicago

ONT - ORD

ONTORD

Ontario

mar. 6/10

7:20 pm-5:40 am

1 stop8h 20m

Chicago O'Hare Intl

mar. 6/17

5:54 pm-12:13 am

1 stop8h 19m

$266

Flights are sorted by cheapest round-trip flights first.

Deals found on 5/12

Showing 1-10 of 50 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 $321). 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 mayo 12, 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 mayo 12, 2025.
Get a feel of what it's like to fly with Alaska Airlines, Southwest 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.
Alaska Airlines
8.0
Very good
10,000 reviews

Comfort

7.9

Boarding

8.1

Overall

8.0

Crew

8.5

Entertainment

7.1

Food

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Alaska Airlines
8.0
Very good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Comfort

7.9

Boarding

8.1

Overall

8.0

Crew

8.5

Entertainment

7.1

Food

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Southwest
8.0
Very good
4,290 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Comfort

7.9

Boarding

8.1

Overall

8.0

Crew

8.5

Entertainment

7.1

Food

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Delta
8.0
Very good
7,950 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Comfort

7.9

Boarding

8.1

Overall

8.0

Crew

8.5

Entertainment

7.1

Food

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Hawaiian Airlines
7.9
Good
2,431 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Comfort

7.9

Boarding

8.1

Overall

8.0

Crew

8.5

Entertainment

7.1

Food

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
United Airlines
7.4
Good
8,724 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Comfort

7.9

Boarding

8.1

Overall

8.0

Crew

8.5

Entertainment

7.1

Food

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.

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?

    $104 is the cheapest one-way deal found within the past few days, from Frontier. You may also be able to find cheap deals on Southwest and United Airlines, with prices starting from $114 and $114, 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 $706, 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 $237 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 $321). 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.

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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 6 airlines flying from Ontario to Illinois

Discover the top 6 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 mayo 12, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$74Average$177FlexibilityNo cancel feeOn-time65%
FrontierCheapest$108Average$211FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$227Average$476FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$237Average$438FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$244Average$494FlexibilityNo cancel feeOn-time71%
DeltaCheapest$245Average$418FlexibilityNo cancel feeOn-timeN/A

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