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$390+ Cheap flights from Islip to Ontario (ISP - ONT)

This is the cheapest round-trip flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 10/3. Fares are subject to change and may not be available on all flights or dates of travel.
ISP — ONT
Oct 17 — Oct 241
Fri 10/17
Fri 10/24
1 adult, Economy
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Cheap flight deals from Islip to Ontario

Discover tips and strategies to find the most affordable flight options for your journey from Islip (ISP) 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 September 17, 2025.

Round-trip from

$390
(Frontier)

Popular in

December

Cheapest in

January

Average price

$317
From Islip Long Island to Ontario
Search Deals
Highest demand for flights based on searches. 8% potential increase in price ($33 potential increase over avg. RT price).
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Cheapest flight prices on average. 3% potential price decrease ($11 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in September 2025
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Find flight deals from Islip to Ontario

Cheapest flights from Islip to Ontario
Explore the most affordable flight options available from Islip to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 17, 2025.

This Frontier deal was found by Cheapflights users on 9/17. 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 10/39:49 amISP - ONT
2 stops11h 46mFrontier
Thu 10/1612:32 pmONT - ISP
2 stops19h 05mFrontier
Deal found 9/17$390
This Booking.com deal was found by Cheapflights users on 9/16. 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.
Tue 10/149:37 pmISP - ONT
2 stops53h 13mFrontier
Tue 10/217:04 amONT - ISP
2 stops24h 53mFrontier
Deal found 9/16$444
This Booking.com deal was found by Cheapflights users on 9/17. 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.
Fri 10/244:58 pmISP - ONT
2 stops41h 51mFrontier
Sun 10/2612:49 pmONT - ISP
2 stops18h 48mFrontier
Deal found 9/17$476
This Frontier deal was found by Cheapflights users on 9/16. 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 10/211:40 amISP - ONT
2 stops23h 13mFrontier
Mon 10/64:08 pmONT - ISP
2 stops19h 05mFrontier
Deal found 9/16$480
This Frontier deal was found by Cheapflights users on 9/16. 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.
Tue 10/1410:39 amISP - ONT
2 stops16h 11mFrontier
Sun 10/1912:49 pmONT - ISP
2 stops17h 15mFrontier
Deal found 9/16$530

Cheapflights Fare Finder

 
Customize your flight search to find flights from Islip 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 September 17, 2025.
Use the filters below to find and compare flights from Islip to Ontario that are best for you.

Fly from

Islip

Fly to

Ontario

Route

Depart

Return

Price

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Fri 10/3

9:49 am-6:35 pm

2 stops11h 46m

Ontario

Thu 10/16

12:32 pm-10:37 am

2 stops19h 05m

$390

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Tue 10/14

9:37 pm-11:50 pm

2 stops53h 13m

Ontario

Tue 10/21

7:04 am-10:57 am

2 stops24h 53m

$444

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Fri 10/24

4:58 pm-7:49 am

2 stops41h 51m

Ontario

Sun 10/26

12:49 pm-10:37 am

2 stops18h 48m

$476

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Thu 10/2

11:40 am-7:53 am

2 stops23h 13m

Ontario

Mon 10/6

4:08 pm-2:13 pm

2 stops19h 05m

$480

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Tue 10/14

10:39 am-11:50 pm

2 stops16h 11m

Ontario

Sun 10/19

12:49 pm-9:04 am

2 stops17h 15m

$530

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Sat 11/1

7:30 am-10:31 pm

2 stops18h 01m

$473

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Thu 10/2

4:33 pm-12:13 pm

2 stops22h 40m

$513

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Sun 10/5

4:33 pm-12:51 pm

2 stops23h 18m

$635

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Wed 10/8

2:19 pm-11:51 pm

2 stops12h 32m

$760

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Fri 12/26

12:40 pm-9:07 pm

2 stops11h 27m

$993

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/17

Best time to book a flight from Islip to Ontario

Have a flexible travel schedule? Discover the best time to fly to Ontario from Islip 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 Islip to Ontario

What is the cheapest month to book a flight from Islip to Ontario?

Currently, August is the cheapest month in which you can book a flight from Islip to Ontario (average of $246). Flying from Islip to Ontario in March is currently the most expensive (average of $327). 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.

Related info for your journey

Find useful and relevant information for your journey from Islip to Ontario. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • How long is the flight from Islip to Ontario?

    For as low as $390, Frontier can have you in Ontario from Islip in 11h 46m. The distance from Islip to Ontario is about 2457 mi.

  • Can I find deals for flights from Islip to Ontario that include hotel bookings?

    Yes. In addition to deals on Islip to Ontario flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Islip to Ontario?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Islip to Ontario.

  • Can I find deals for business class flights from Islip to Ontario?

    Yes. Cheapflights offers flight deals from Islip 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 Islip to Ontario?

    Currently, August is the cheapest month in which you can book a flight from Islip to Ontario (average of $246). Flying from Islip to Ontario in March is currently the most expensive (average of $327). 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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