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$55+ 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 2/22. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — ONT
Jan 27 — Feb 31
Mon 1/27
Mon 2/3
1 adult, Economy
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Cheap flight deals from Illinois to Ontario

Discover tips and strategies to find the most affordable flight options for your journey from Illinois (USIL) to Ontario (ONT). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated January 22, 2025.

Round-trip from

$110
(Frontier)

One-way from

$55
(Frontier)

Good round-trip deal

$429 or less

Good one-way deal

$169 or less
From Illinois to Ontario
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One-way flight from Illinois to Ontario
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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 January 22, 2025.

This Frontier deal was found by Cheapflights users on 1/22. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 2/57:09 pmSTL - ONT
1 stop6h 38mFrontier
Tue 2/1112:59 amONT - STL
1 stop6h 17mFrontier
Deal found 1/22$110
This Gotogate deal was found by Cheapflights users on 1/22. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 3/136:40 amMDW - ONT
1 stop19h 29mFrontier
Fri 3/219:35 pmONT - MDW
1 stop5h 56mFrontier
Deal found 1/22$171
This Justfly.com deal was found by Cheapflights users on 1/20. 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 Justfly.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 1/276:20 amORD - ONT
1 stop16h 26mFrontier
Wed 1/2912:34 pmONT - ORD
1 stop26h 51mFrontier
Deal found 1/20$171
This American Airlines deal was found by Cheapflights users on 1/21. 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 8/195:00 amORD - ONT
1 stop8h 27mAmerican Airlines
Sun 8/248:01 pmONT - ORD
1 stop7h 27mAmerican Airlines
Deal found 1/21$247
This Delta deal was found by Cheapflights users on 1/22. 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.
Tue 3/45:05 pmMDW - ONT
1 stop7h 47mDelta
Wed 3/51:10 pmONT - MDW
1 stop7h 10mDelta
Deal found 1/22$257
This Delta deal was found by Cheapflights users on 1/22. 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.
Mon 3/37:20 amORD - ONT
1 stop7h 04mDelta
Wed 3/121:30 pmONT - ORD
1 stop6h 15mDelta
Deal found 1/22$257
This Southwest deal was found by Cheapflights users on 1/22. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 2/157:05 pmORD - ONT
1 stop6h 20mSouthwest
Sat 2/225:05 amONT - ORD
2 stops9h 40mSouthwest
Deal found 1/22$274
This United Airlines deal was found by Cheapflights users on 1/22. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/128:50 amPIA - ONT
1 stop5h 48mUnited Airlines
Fri 4/186:39 pmONT - PIA
2 stops13h 33mUnited Airlines
Deal found 1/22$294
This United Airlines deal was found by Cheapflights users on 1/21. 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.
Sat 6/216:30 amORD - ONT
1 stop8h 04mUnited Airlines
Sat 6/281:00 pmONT - ORD
1 stop7h 25mUnited Airlines
Deal found 1/21$296
This Alaska Airlines deal was found by Cheapflights users on 1/20. 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.
Mon 2/107:45 amORD - ONT
1 stop28h 53mAlaska Airlines
Wed 2/1211:33 amONT - ORD
1 stop10h 26mAlaska Airlines
Deal found 1/20$317
This Expedia deal was found by Cheapflights users on 1/22. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 2/77:25 amORD - ONT
1 stop12h 03mMultiple Airlines
Sun 2/97:00 amONT - ORD
2 stops14h 59mMultiple Airlines
Deal found 1/22$324
This Delta deal was found by Cheapflights users on 1/22. 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 2/155:00 pmSTL - ONT
1 stop8h 26mDelta
Tue 2/181:05 pmONT - STL
1 stop8h 31mDelta
Deal found 1/22$345

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 January 22, 2025.

Fly from

Any airport

Fly to

Any airport

Route

Depart

Return

Price

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Wed 2/5

7:09 pm-11:47 pm

1 stop6h 38m

Ontario

Tue 2/11

12:59 am-9:16 am

1 stop6h 17m

$110

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Thu 3/13

6:40 am-12:09 am

1 stop19h 29m

Ontario

Fri 3/21

9:35 pm-5:31 am

1 stop5h 56m

$171

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Fri 3/14

7:59 pm-8:36 pm

1 stop26h 37m

Ontario

Mon 3/17

4:39 pm-12:44 am

1 stop6h 05m

$171

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Wed 3/26

12:00 pm-8:53 pm

1 stop10h 53m

Ontario

Tue 4/1

7:35 pm-5:08 am

1 stop7h 33m

$247

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Tue 3/4

5:05 pm-10:52 pm

1 stop7h 47m

Ontario

Wed 3/5

1:10 pm-10:20 pm

1 stop7h 10m

$257

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Sun 2/23

7:18 pm-11:51 pm

1 stop6h 33m

Ontario

Fri 2/28

1:21 pm-9:27 pm

1 stop6h 06m

$257

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Sat 2/15

7:05 pm-11:25 pm

1 stop6h 20m

Ontario

Sat 2/22

5:05 am-4:45 pm

2 stops9h 40m

$274

PeoriaOntario

PIA - ONT

PIAONT

Greater Peoria

Sat 4/12

8:50 am-12:38 pm

1 stop5h 48m

Ontario

Fri 4/18

6:39 pm-10:12 am

2 stops13h 33m

$294

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Fri 2/7

7:25 am-5:28 pm

1 stop12h 03m

Ontario

Sun 2/9

7:00 am-11:59 pm

2 stops14h 59m

$324

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Mon 2/17

9:00 am-11:30 am

Nonstop4h 30m

Ontario

Sat 2/22

5:05 am-2:45 pm

1 stop7h 40m

$330

Flights are sorted by cheapest round-trip flights first.

Deals found on 1/22

Showing 1-10 of 45 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.

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 $310). 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 January 22, 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 January 22, 2025.
Get a feel of what it's like to fly with Frontier, Delta and Southwest 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
4,654 reviews

Boarding

8.2

Food

7.2

Overall

8.1

Entertainment

7.7

Comfort

8.1

Crew

8.7

Reviews

1 / 10

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
4,654 reviews
Southwest
8.1
Very good
4,654 reviews

Boarding

8.2

Food

7.2

Overall

8.1

Entertainment

7.7

Comfort

8.1

Crew

8.7

Reviews

1 / 10

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
9,707 reviews
Southwest
8.1
Very good
4,654 reviews

Boarding

8.2

Food

7.2

Overall

8.1

Entertainment

7.7

Comfort

8.1

Crew

8.7

Reviews

1 / 10

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
8,514 reviews
Southwest
8.1
Very good
4,654 reviews

Boarding

8.2

Food

7.2

Overall

8.1

Entertainment

7.7

Comfort

8.1

Crew

8.7

Reviews

1 / 10

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
8,975 reviews
Southwest
8.1
Very good
4,654 reviews

Boarding

8.2

Food

7.2

Overall

8.1

Entertainment

7.7

Comfort

8.1

Crew

8.7

Reviews

1 / 10

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

American Airlines
7.2
Good
10,000 reviews
Southwest
8.1
Very good
4,654 reviews

Boarding

8.2

Food

7.2

Overall

8.1

Entertainment

7.7

Comfort

8.1

Crew

8.7

Reviews

1 / 10

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?

    $55 is the cheapest one-way deal found within the past few days, from Frontier. You may also be able to find cheap deals on Alaska Airlines and United Airlines, with prices starting from $123 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 $310). 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 January 22, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$121Average$203FlexibilityNo cancel feeOn-time62%
American AirlinesCheapest$204Average$583FlexibilityNo cancel feeOn-time71%
DeltaCheapest$256Average$450FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$256Average$549FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$256Average$500FlexibilityNo cancel feeOn-time63%
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