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$38+ 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 4/1. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — ONT
Feb 25 — Mar 41
Tue 2/25
Tue 3/4
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 February 20, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$110
(Frontier)

One-way from

$38
(Trip.com)

Popular in

March

Cheapest in

September

Average price

$288

Good round-trip deal

$330 or less

Good one-way deal

$226 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 ($18 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 February 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 February 20, 2025.

This Frontier deal was found by Cheapflights users on 2/19. 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 5/84:07 pmSTL - ONT
1 stop9h 52mFrontier
Mon 5/1210:52 amONT - STL
1 stop8h 13mFrontier
Deal found 2/19$110
This eDestinos deal was found by Cheapflights users on 2/19. 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 eDestinos is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/168:40 amORD - ONT
1 stop11h 07mFrontier
Tue 5/2710:17 pmONT - ORD
1 stop28h 54mFrontier
Deal found 2/19$133
This Mytrip deal was found by Cheapflights users on 2/19. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 3/65:30 amMDW - ONT
1 stop12h 54mFrontier
Tue 3/1112:59 amONT - MDW
1 stop21h 18mFrontier
Deal found 2/19$133
This Travelocity deal was found by Cheapflights users on 2/20. 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 Travelocity is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/166:40 amORD - ONT
1 stop9h 47mMultiple Airlines
Wed 4/234:29 pmONT - ORD
1 stop11h 36mMultiple Airlines
Deal found 2/20$203
This United Airlines deal was found by Cheapflights users on 2/20. 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.
Thu 6/58:20 pmORD - ONT
Nonstop4h 31mUnited Airlines
Mon 6/97:00 amONT - ORD
Nonstop4h 03mUnited Airlines
Deal found 2/20$228
This American Airlines deal was found by Cheapflights users on 2/19. 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 4/228:15 amORD - ONT
1 stop7h 34mAmerican Airlines
Sun 4/277:25 pmONT - ORD
1 stop7h 52mAmerican Airlines
Deal found 2/19$247
This Delta deal was found by Cheapflights users on 2/20. 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 3/267:30 amORD - ONT
1 stop11h 12mDelta
Tue 4/15:30 pmONT - ORD
2 stops13h 48mDelta
Deal found 2/20$248
This Delta deal was found by Cheapflights users on 2/20. 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.
Mon 4/144:59 pmMDW - ONT
1 stop7h 37mDelta
Wed 4/2312:10 pmONT - MDW
1 stop8h 16mDelta
Deal found 2/20$257
This eDestinos deal was found by Cheapflights users on 2/19. 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 eDestinos is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 4/66:35 amSTL - ONT
2 stops26h 50mMultiple Airlines
Sat 4/1212:59 amONT - STL
1 stop8h 23mMultiple Airlines
Deal found 2/19$272
This Delta deal was found by Cheapflights users on 2/20. 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.
Mon 4/216:00 amSTL - ONT
2 stops9h 55mDelta
Tue 4/2911:45 amONT - STL
2 stops9h 49mDelta
Deal found 2/20$286
This Alaska Airlines deal was found by Cheapflights users on 2/20. 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 9/27:45 amORD - ONT
1 stop9h 27mAlaska Airlines
Thu 9/46:00 pmONT - ORD
1 stop9h 04mAlaska Airlines
Deal found 2/20$287
This American Airlines deal was found by Cheapflights users on 2/20. 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.
Wed 5/1411:15 amMLI - ONT
2 stops9h 08mAmerican Airlines
Tue 5/2010:00 amONT - MLI
2 stops9h 58mAmerican Airlines
Deal found 2/20$299

Find flights from Illinois to Ontario within your budget

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 February 20, 2025.

Fly from

Illinois

Fly to

Ontario

Route

Depart

Return

Price

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Sat 5/3

6:53 pm-11:59 pm

1 stop7h 06m

Ontario

Tue 5/6

12:59 am-9:09 am

1 stop6h 10m

$110

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Fri 5/16

8:40 am-5:47 pm

1 stop11h 07m

Ontario

Mon 5/26

12:59 am-12:08 am

1 stop21h 09m

$133

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Thu 3/6

5:30 am-4:24 pm

1 stop12h 54m

Ontario

Tue 3/11

12:59 am-12:17 am

1 stop21h 18m

$133

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Wed 4/16

6:40 am-2:27 pm

1 stop9h 47m

Ontario

Wed 4/23

4:29 pm-6:05 am

1 stop11h 36m

$203

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Fri 5/23

7:55 pm-10:26 pm

Nonstop4h 31m

Ontario

Mon 5/26

7:00 am-1:03 pm

Nonstop4h 03m

$228

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Tue 4/15

6:00 am-11:59 am

1 stop7h 59m

Ontario

Tue 4/22

4:35 pm-12:40 am

1 stop6h 05m

$247

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Tue 4/15

5:05 pm-9:30 pm

1 stop6h 25m

Ontario

Tue 4/22

3:10 pm-10:50 pm

1 stop5h 40m

$252

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Sat 4/12

7:45 am-12:26 pm

1 stop6h 41m

Ontario

Tue 4/22

11:45 am-11:59 pm

1 stop10h 14m

$257

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Mon 4/14

4:59 pm-10:36 pm

1 stop7h 37m

Ontario

Wed 4/23

12:10 pm-10:26 pm

1 stop8h 16m

$257

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Sun 4/6

6:35 am-7:25 am

2 stops26h 50m

Ontario

Sat 4/12

12:59 am-11:22 am

1 stop8h 23m

$272

Flights are sorted by cheapest round-trip flights first.

Deals found on 2/19

Showing 1-10 of 43 results
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5

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.

Travel insights for flights from Illinois to Ontario

Get recent, data-driven insights about flights from Illinois to Ontario including ideal travel times, pricing trends, and more.

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 $315). 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 February 20, 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 February 20, 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
4,411 reviews

Food

7.1

Boarding

8.2

Overall

8.1

Entertainment

7.6

Comfort

8.1

Crew

8.7

Reviews

1 / 20

2.0
Mediocre

Bhoopal,Nov 2024

STL - BOS

Flight was delayed by one hour and 40 minutes. Also baggage was delivered late at Boston. This delay made me miss my connection from Boston to Hyderabad

Southwest
8.1
Very good
4,411 reviews
Southwest
8.1
Very good
4,411 reviews

Food

7.1

Boarding

8.2

Overall

8.1

Entertainment

7.6

Comfort

8.1

Crew

8.7

Reviews

1 / 20

2.0
Mediocre

Bhoopal,Nov 2024

STL - BOS

Flight was delayed by one hour and 40 minutes. Also baggage was delivered late at Boston. This delay made me miss my connection from Boston to Hyderabad

Alaska Airlines
8.0
Very good
9,697 reviews
Southwest
8.1
Very good
4,411 reviews

Food

7.1

Boarding

8.2

Overall

8.1

Entertainment

7.6

Comfort

8.1

Crew

8.7

Reviews

1 / 20

2.0
Mediocre

Bhoopal,Nov 2024

STL - BOS

Flight was delayed by one hour and 40 minutes. Also baggage was delivered late at Boston. This delay made me miss my connection from Boston to Hyderabad

Delta
8.0
Very good
8,219 reviews
Southwest
8.1
Very good
4,411 reviews

Food

7.1

Boarding

8.2

Overall

8.1

Entertainment

7.6

Comfort

8.1

Crew

8.7

Reviews

1 / 20

2.0
Mediocre

Bhoopal,Nov 2024

STL - BOS

Flight was delayed by one hour and 40 minutes. Also baggage was delivered late at Boston. This delay made me miss my connection from Boston to Hyderabad

Hawaiian Airlines
7.9
Good
2,317 reviews
Southwest
8.1
Very good
4,411 reviews

Food

7.1

Boarding

8.2

Overall

8.1

Entertainment

7.6

Comfort

8.1

Crew

8.7

Reviews

1 / 20

2.0
Mediocre

Bhoopal,Nov 2024

STL - BOS

Flight was delayed by one hour and 40 minutes. Also baggage was delivered late at Boston. This delay made me miss my connection from Boston to Hyderabad

United Airlines
7.4
Good
8,765 reviews
Southwest
8.1
Very good
4,411 reviews

Food

7.1

Boarding

8.2

Overall

8.1

Entertainment

7.6

Comfort

8.1

Crew

8.7

Reviews

1 / 20

2.0
Mediocre

Bhoopal,Nov 2024

STL - BOS

Flight was delayed by one hour and 40 minutes. Also baggage was delivered late at Boston. This delay made me miss my connection from Boston to Hyderabad

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?

    $38 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 American Airlines, with prices starting from $114 and $124, 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.

  • 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 $315). 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 February 20, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$121Average$202FlexibilityNo cancel feeOn-time62%
American AirlinesCheapest$204Average$588FlexibilityNo cancel feeOn-time71%
DeltaCheapest$256Average$450FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$256Average$510FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$256Average$488FlexibilityNo cancel feeOn-time63%
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