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$737+ Cheap flights from Islip, NY 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 12/26. Fares are subject to change and may not be available on all flights or dates of travel.
ISP — ONT
Dec 19 — Dec 261
Fri 12/19
Fri 12/26
1 adult, Economy
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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 November 19, 2025.

This Southwest deal was found by Cheapflights users on 11/16. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/265:40 amISP - ONT
2 stops10h 00mSouthwest
Fri 1/97:00 amONT - ISP
2 stops11h 55mSouthwest
Deal found 11/16$737
This eDestinos deal was found by Cheapflights users on 11/16. 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 eDestinos is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/2612:30 pmISP - ONT
2 stops24h 30mMultiple Airlines
Fri 1/93:49 pmONT - ISP
3 stops49h 02mMultiple Airlines
Deal found 11/16$1,401

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 November 19, 2025.

Most accurate provider

eDreams
3 stars

Most trusted provider

eDreams
3 stars

Round-trip from

$737
(Southwest)

Popular in

December

Cheapest in

September

Average price

$385
Provider with most accurate pricing for Islip Long Island-Ontario flight deals.
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Provider most trusted by Cheapflights users for Islip Long Island-Ontario flights.
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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).
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($11 potential savings vs. average RT price).
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Average for round-trip flights in November 2025
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Compare providers for flights from Islip to Ontario

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Islip to Ontario in November.
ProviderPrice AccuracyTrust Score*
FlightHubPrice Accuracy3 starsTrust Score*1 star
ExpediaPrice Accuracy2 starsTrust Score*3 stars
eDreamsPrice Accuracy3 starsTrust Score*3 stars

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on Islip, New York-Ontario flights, users find the pricing of eDreams to be most consistent on Cheapflights vs. eDreams Users can find the same prices on Islip, New York-Ontario flight deals on Cheapflights vs. eDreams >95% of the time. Price accuracy is based on data collected from Islip, New York-Ontario flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Islip, New York-Ontario flights, Cheapflights users trust eDreams the most. eDreams has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Islip, New York-Ontario flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

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, New York to Ontario?

Currently, August is the cheapest month in which you can book a flight from Islip, New York to Ontario (average of $90). Flying from Islip, New York to Ontario in December is currently the most expensive (average of $176). 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.

  • 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, New York to Ontario?

    Currently, August is the cheapest month in which you can book a flight from Islip, New York to Ontario (average of $90). Flying from Islip, New York to Ontario in December is currently the most expensive (average of $176). 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.

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