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$105+ 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 4/12. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — ONT
Apr 2 — Apr 91
Wed 4/2
Wed 4/9
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 March 28, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$227
(United Airlines)

One-way from

$105
(Trip.com)

Popular in

December

Cheapest in

September

Average price

$359

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. 6% potential increase in price ($19 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 March 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 March 28, 2025.

This United Airlines deal was found by Cheapflights users on 3/26. 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.
Fri 10/107:55 pmORD - ONT
Nonstop4h 31mUnited Airlines
Sun 10/127:00 amONT - ORD
Nonstop4h 03mUnited Airlines
Deal found 3/26$227
This Frontier 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/185:01 amORD - ONT
1 stop13h 50mFrontier
Sun 4/208:29 amONT - ORD
1 stop10h 48mFrontier
Deal found 3/28$238
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.
Thu 4/178:50 pmMDW - ONT
1 stop12h 35mFrontier
Sun 4/208:29 amONT - MDW
1 stop11h 58mFrontier
Deal found 3/27$238
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.
Thu 5/19:55 pmSTL - ONT
1 stop11h 29mFrontier
Fri 5/912:59 amONT - STL
1 stop7h 00mFrontier
Deal found 3/27$238
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.
Tue 5/66:00 amORD - ONT
1 stop11h 32mAlaska Airlines
Mon 5/126:24 pmONT - ORD
1 stop9h 41mAlaska Airlines
Deal found 3/27$246
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.
Tue 7/112:48 pmORD - ONT
1 stop10h 45mAmerican Airlines
Tue 7/154:45 pmONT - ORD
1 stop5h 52mAmerican Airlines
Deal found 3/27$247
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.
Wed 5/217:30 amORD - ONT
1 stop6h 45mDelta
Sun 5/251:10 pmONT - ORD
1 stop6h 30mDelta
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.
Thu 8/211:00 pmMDW - ONT
2 stops11h 29mDelta
Mon 8/2510:59 pmONT - MDW
2 stops11h 31mDelta
Deal found 3/27$267
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.
Tue 5/206:55 pmORD - ONT
1 stop6h 05mSouthwest
Thu 5/293:55 pmONT - ORD
1 stop5h 45mSouthwest
Deal found 3/27$283
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.
Fri 5/98:25 amMDW - ONT
1 stop7h 45mSouthwest
Tue 5/136:00 amONT - MDW
Nonstop3h 50mSouthwest
Deal found 3/27$322
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.
Sat 4/123:37 pmPIA - ONT
1 stop8h 21mAmerican Airlines
Wed 4/1611:59 pmONT - PIA
1 stop8h 19mAmerican Airlines
Deal found 3/27$339
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.
Thu 5/17:15 pmSTL - ONT
1 stop6h 26mDelta
Sat 5/31:20 pmONT - STL
1 stop5h 43mDelta
Deal found 3/27$341

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 March 28, 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

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Sat 5/24

7:55 pm-10:26 pm

Nonstop4h 31m

Ontario

Sun 6/1

7:00 am-1:03 pm

Nonstop4h 03m

$227

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Fri 4/18

5:01 am-4:51 pm

1 stop13h 50m

Ontario

Sun 4/20

8:29 am-9:17 pm

1 stop10h 48m

$238

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Thu 4/17

8:50 pm-7:25 am

1 stop12h 35m

Ontario

Sun 4/20

8:29 am-10:27 pm

1 stop11h 58m

$238

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Thu 5/1

9:55 pm-7:24 am

1 stop11h 29m

Ontario

Fri 5/9

12:59 am-9:59 am

1 stop7h 00m

$238

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Tue 5/6

6:00 am-3:32 pm

1 stop11h 32m

Ontario

Mon 5/12

6:24 pm-6:05 am

1 stop9h 41m

$246

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Tue 7/1

12:48 pm-9:33 pm

1 stop10h 45m

Ontario

Tue 7/15

4:45 pm-12:37 am

1 stop5h 52m

$247

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Wed 5/21

7:30 am-12:15 pm

1 stop6h 45m

Ontario

Sun 5/25

1:10 pm-9:40 pm

1 stop6h 30m

$257

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Thu 8/21

1:00 pm-10:29 pm

2 stops11h 29m

Ontario

Mon 8/25

10:59 pm-12:30 pm

2 stops11h 31m

$267

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Tue 5/20

6:55 pm-11:00 pm

1 stop6h 05m

Ontario

Thu 5/29

3:55 pm-11:40 pm

1 stop5h 45m

$283

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Fri 5/9

8:25 am-2:10 pm

1 stop7h 45m

Ontario

Tue 5/13

6:00 am-11:50 am

Nonstop3h 50m

$322

Flights are sorted by cheapest round-trip flights first.

Deals found on 3/27

Showing 1-10 of 46 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 $326). 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 March 28, 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 March 28, 2025.
Get a feel of what it's like to fly with Southwest, Alaska Airlines 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.
Southwest
8.1
Very good
4,274 reviews

Comfort

8.1

Crew

8.7

Food

7.1

Boarding

8.2

Entertainment

7.6

Overall

8.1

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
4,274 reviews
Southwest
8.1
Very good
4,274 reviews

Comfort

8.1

Crew

8.7

Food

7.1

Boarding

8.2

Entertainment

7.6

Overall

8.1

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
4,274 reviews

Comfort

8.1

Crew

8.7

Food

7.1

Boarding

8.2

Entertainment

7.6

Overall

8.1

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
7,897 reviews
Southwest
8.1
Very good
4,274 reviews

Comfort

8.1

Crew

8.7

Food

7.1

Boarding

8.2

Entertainment

7.6

Overall

8.1

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
2,336 reviews
Southwest
8.1
Very good
4,274 reviews

Comfort

8.1

Crew

8.7

Food

7.1

Boarding

8.2

Entertainment

7.6

Overall

8.1

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
4,274 reviews

Comfort

8.1

Crew

8.7

Food

7.1

Boarding

8.2

Entertainment

7.6

Overall

8.1

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 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?

    $105 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 Hawaiian Airlines, with prices starting from $114 and $123, 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 $255. The most popular route, (Chicago O'Hare Intl - Ontario), can usually be booked for $227.

  • 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 $326). 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 March 28, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$121Average$199FlexibilityNo cancel feeOn-time62%
American AirlinesCheapest$204Average$573FlexibilityNo cancel feeOn-time71%
DeltaCheapest$246Average$450FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$256Average$485FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$256Average$478FlexibilityNo cancel feeOn-time63%
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