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Ontario

$87+ 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 5/10. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — ONT
May 6 — May 131
Tue 5/6
Tue 5/13
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 May 1, 2025.

Most accurate provider

Mytrip
3 stars

Most trusted provider

Mytrip
3 stars

Round-trip from

$178
(Frontier)

One-way from

$87
(Cheapflightsfares)

Popular in

December

Cheapest in

September

Average price

$261

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. 7% potential increase in price ($24 potential increase over avg. RT price).
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Cheapest flight prices on average. 3% potential price decrease ($9 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 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 May 1, 2025.

This Frontier deal was found by Cheapflights users on 5/1. 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 5/29:55 pmSTL - ONT
1 stop11h 29mFrontier
Sun 5/412:59 amONT - STL
1 stop6h 10mFrontier
Deal found 5/1$178
This Booking.com deal was found by Cheapflights users on 4/30. 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.
Wed 5/286:00 amORD - ONT
1 stop29h 15mFrontier
Fri 5/3012:59 amONT - ORD
1 stop20h 53mFrontier
Deal found 4/30$208
This CheapOair deal was found by Cheapflights users on 5/1. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/312:44 pmMDW - ONT
1 stop20h 28mFrontier
Mon 6/212:59 amONT - MDW
1 stop17h 54mFrontier
Deal found 5/1$208
This United Airlines deal was found by Cheapflights users on 4/30. 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 6/57:55 pmORD - ONT
Nonstop4h 31mUnited Airlines
Wed 6/116:41 pmONT - ORD
1 stop8h 48mUnited Airlines
Deal found 4/30$237
This Southwest deal was found by Cheapflights users on 4/30. 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.
Wed 6/115:15 amMDW - ONT
1 stop5h 40mSouthwest
Sun 6/155:00 amONT - MDW
Nonstop3h 50mSouthwest
Deal found 4/30$237
This Alaska Airlines deal was found by Cheapflights users on 4/30. 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 9/96:20 amORD - ONT
1 stop9h 49mAlaska Airlines
Sat 11/86:55 pmONT - ORD
1 stop8h 09mAlaska Airlines
Deal found 4/30$246
This American Airlines deal was found by Cheapflights users on 4/30. 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 6/144:45 pmORD - ONT
1 stop6h 53mAmerican Airlines
Sat 6/214:50 pmONT - ORD
1 stop5h 42mAmerican Airlines
Deal found 4/30$247
This Delta deal was found by Cheapflights users on 4/30. 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 9/131:16 pmORD - ONT
1 stop8h 26mDelta
Wed 11/59:55 amONT - ORD
1 stop6h 02mDelta
Deal found 4/30$257
This Delta deal was found by Cheapflights users on 4/30. 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 6/149:24 amMDW - ONT
2 stops8h 53mDelta
Sat 6/2111:49 amONT - MDW
1 stop7h 56mDelta
Deal found 4/30$262
This Hawaiian Airlines deal was found by Cheapflights users on 4/30. 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.
Thu 8/216:20 amORD - ONT
1 stop9h 49mHawaiian Airlines
Mon 8/2511:39 amONT - ORD
1 stop10h 20mHawaiian Airlines
Deal found 4/30$286
This Delta deal was found by Cheapflights users on 4/30. 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 7/235:23 pmSTL - ONT
1 stop7h 04mDelta
Tue 7/297:05 amONT - STL
1 stop7h 13mDelta
Deal found 4/30$307
This eDestinos deal was found by Cheapflights users on 4/30. 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 5/96:53 pmSTL - ONT
1 stop7h 06mMultiple Airlines
Sun 5/1112:16 pmONT - STL
3 stops29h 54mMultiple Airlines
Deal found 4/30$319

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 May 1, 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

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Sun 5/11

9:55 pm-7:24 am

1 stop11h 29m

Ontario

Tue 5/13

12:59 am-9:59 am

1 stop7h 00m

$178

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Wed 5/28

6:00 am-9:15 am

1 stop29h 15m

Ontario

Fri 5/30

12:59 am-11:52 pm

1 stop20h 53m

$208

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Sat 5/31

2:44 pm-9:12 am

1 stop20h 28m

Ontario

Mon 6/2

12:59 am-8:53 pm

1 stop17h 54m

$208

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Mon 6/2

7:55 pm-10:26 pm

Nonstop4h 31m

Ontario

Sun 6/8

7:00 am-1:03 pm

Nonstop4h 03m

$227

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Wed 6/11

5:15 am-8:55 am

1 stop5h 40m

Ontario

Sun 6/15

5:00 am-10:50 am

Nonstop3h 50m

$237

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Wed 9/10

6:20 am-2:09 pm

1 stop9h 49m

Ontario

Wed 11/5

6:00 pm-5:04 am

1 stop9h 04m

$246

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Sat 6/14

4:45 pm-9:38 pm

1 stop6h 53m

Ontario

Sat 6/21

4:50 pm-12:32 am

1 stop5h 42m

$247

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Sat 9/13

1:16 pm-7:42 pm

1 stop8h 26m

Ontario

Wed 11/5

9:55 am-5:57 pm

1 stop6h 02m

$257

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Sat 6/14

9:24 am-4:17 pm

2 stops8h 53m

Ontario

Sat 6/21

11:49 am-9:45 pm

1 stop7h 56m

$262

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Thu 8/21

6:20 am-2:09 pm

1 stop9h 49m

Ontario

Mon 8/25

11:39 am-11:59 pm

1 stop10h 20m

$286

Flights are sorted by cheapest round-trip flights first.

Deals found on 4/30

Showing 1-10 of 48 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 $328). 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 May 1, 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 May 1, 2025.
Get a feel of what it's like to fly with Alaska Airlines, Southwest 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.
Alaska Airlines
8.0
Very good
9,972 reviews

Food

7.1

Crew

8.5

Overall

8.0

Comfort

7.9

Boarding

8.1

Entertainment

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
9,972 reviews
Alaska Airlines
8.0
Very good
9,972 reviews

Food

7.1

Crew

8.5

Overall

8.0

Comfort

7.9

Boarding

8.1

Entertainment

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
4,293 reviews
Alaska Airlines
8.0
Very good
9,972 reviews

Food

7.1

Crew

8.5

Overall

8.0

Comfort

7.9

Boarding

8.1

Entertainment

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
7,934 reviews
Alaska Airlines
8.0
Very good
9,972 reviews

Food

7.1

Crew

8.5

Overall

8.0

Comfort

7.9

Boarding

8.1

Entertainment

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
2,409 reviews
Alaska Airlines
8.0
Very good
9,972 reviews

Food

7.1

Crew

8.5

Overall

8.0

Comfort

7.9

Boarding

8.1

Entertainment

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
8,696 reviews
Alaska Airlines
8.0
Very good
9,972 reviews

Food

7.1

Crew

8.5

Overall

8.0

Comfort

7.9

Boarding

8.1

Entertainment

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 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?

    $87 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 $114, 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 $238. 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 $328). 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 May 1, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$123Average$207FlexibilityNo cancel feeOn-time62%
American AirlinesCheapest$204Average$578FlexibilityNo cancel feeOn-time71%
DeltaCheapest$246Average$450FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$246Average$406FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$256Average$482FlexibilityNo cancel feeOn-time63%

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