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Islip

$80+ Cheap flights from St. Louis to Islip (STL - ISP)

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 10/23. Fares are subject to change and may not be available on all flights or dates of travel.
STL — ISP
out 16 — out 231
qui 10/16
qui 10/23
1 adult, Economy
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Cheap flight deals from St. Louis to Islip

Discover tips and strategies to find the most affordable flight options for your journey from St. Louis (STL) to Islip (ISP). 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 setembro 16, 2025.

Round-trip from

$202
(Frontier)

One-way from

$80
(Cheapflightsfares)

Popular in

March

Cheapest in

April

Average price

$516
From Lambert-St Louis to Islip Long Island
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One-way flight from Lambert-St Louis to Islip Long Island
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High demand for flights, 5% potential price rise
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Cheapest flight prices on average. 3% potential price decrease ($12 potential savings vs. average RT price).
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Average for round-trip flights in September 2025
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Find flight deals from St. Louis to Islip

Cheapest flights from St. Louis to Islip
Explore the most affordable flight options available from St. Louis to Islip. Find the lowest fares from popular airlines and budget airlines, with prices last updated on setembro 16, 2025.

This Frontier deal was found by Cheapflights users on 9/15. 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.
qui 10/308:40 pmSTL - ISP
2 stops12h 57mFrontier
dom 11/29:27 pmISP - STL
1 stop13h 13mFrontier
Deal found 9/15$202
This Frontier deal was found by Cheapflights users on 9/14. 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.
seg 9/294:00 pmSTL - ISP
2 stops17h 40mFrontier
sex 10/35:05 pmISP - STL
2 stops17h 01mFrontier
Deal found 9/14$235
This Southwest deal was found by Cheapflights users on 9/15. 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.
qui 12/49:45 amSTL - ISP
1 stop4h 35mSouthwest
seg 12/83:55 pmISP - STL
1 stop7h 05mSouthwest
Deal found 9/15$239
This Frontier deal was found by Cheapflights users on 9/15. 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.
qui 9/2510:49 amSTL - ISP
2 stops22h 51mFrontier
seg 9/295:05 pmISP - STL
2 stops17h 01mFrontier
Deal found 9/15$272
This Southwest deal was found by Cheapflights users on 9/15. 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.
sex 12/56:05 amSTL - ISP
1 stop5h 10mSouthwest
dom 12/73:25 pmISP - STL
1 stop9h 25mSouthwest
Deal found 9/15$282
This Frontier deal was found by Cheapflights users on 9/15. 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.
sex 9/267:55 pmSTL - ISP
2 stops14h 00mFrontier
seg 9/295:05 pmISP - STL
2 stops17h 01mFrontier
Deal found 9/15$291
This Trip.com deal was found by Cheapflights users on 9/14. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
sex 10/176:05 pmSTL - ISP
1 stop15h 32mFrontier
seg 10/204:58 pmISP - STL
2 stops41h 09mFrontier
Deal found 9/14$308
This Southwest deal was found by Cheapflights users on 9/14. 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.
sex 10/174:55 pmSTL - ISP
1 stop5h 50mSouthwest
seg 10/205:30 amISP - STL
1 stop7h 00mSouthwest
Deal found 9/14$370

Cheapflights Fare Finder

 
Customize your flight search to find flights from St. Louis to Islip 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 setembro 16, 2025.
Use the filters below to find and compare flights from St. Louis to Islip that are best for you.

Fly from

St. Louis

Fly to

Islip

Route

Depart

Return

Price

St. LouisIslip

STL - ISP

STLISP

Lambert-St Louis

seg 9/29

4:00 pm-10:40 am

2 stops17h 40m

Islip Long Island

sex 10/3

5:05 pm-9:06 am

2 stops17h 01m

$235

St. LouisIslip

STL - ISP

STLISP

Lambert-St Louis

qui 12/4

9:45 am-3:20 pm

1 stop4h 35m

Islip Long Island

seg 12/8

3:55 pm-10:00 pm

1 stop7h 05m

$239

St. LouisIslip

STL - ISP

STLISP

Lambert-St Louis

qui 9/25

10:49 am-10:40 am

2 stops22h 51m

Islip Long Island

seg 9/29

5:05 pm-9:06 am

2 stops17h 01m

$272

St. LouisIslip

STL - ISP

STLISP

Lambert-St Louis

sex 12/5

6:05 am-12:15 pm

1 stop5h 10m

Islip Long Island

dom 12/7

3:25 pm-11:50 pm

1 stop9h 25m

$282

St. LouisIslip

STL - ISP

STLISP

Lambert-St Louis

sex 9/26

7:55 pm-10:55 am

2 stops14h 00m

Islip Long Island

seg 9/29

5:05 pm-9:06 am

2 stops17h 01m

$291

St. LouisIslip

STL - ISP

STLISP

Lambert-St Louis

sex 10/17

6:05 pm-10:37 am

1 stop15h 32m

Islip Long Island

seg 10/20

4:58 pm-9:07 am

2 stops41h 09m

$308

St. LouisIslip

STL - ISP

STLISP

Lambert-St Louis

sex 10/17

4:55 pm-11:45 pm

1 stop5h 50m

Islip Long Island

seg 10/20

5:30 am-11:30 am

1 stop7h 00m

$370

St. LouisIslip

STL - ISP

STLISP

Lambert-St Louis

qui 10/23

1:41 pm-8:42 pm

1 stop6h 01m

$80

St. LouisIslip

STL - ISP

STLISP

Lambert-St Louis

dom 10/12

1:41 pm-8:52 pm

1 stop6h 11m

$80

St. LouisIslip

STL - ISP

STLISP

Lambert-St Louis

sex 10/3

9:32 pm-10:55 am

1 stop12h 23m

$86

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/14

Showing 1-10 of 13 results
1
2

Best time to book a flight from St. Louis to Islip

Have a flexible travel schedule? Discover the best time to fly to Islip from St. Louis 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 St. Louis to Islip

What is the cheapest month to book a flight from St. Louis to Islip?

Currently, January is the cheapest month in which you can book a flight from St. Louis to Islip (average of $108). Flying from St. Louis to Islip in November is currently the most expensive (average of $213). 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 STL to ISP?

Find hourly flight availability from St. Louis to Islip. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated setembro 16, 2025.

A simple way to save on the total cost of your ticket is to fly from St. Louis to Islip at noon. If you’re flexible enough to do this you can expect to save up to 60% on your trip compared to booking a flight in the morning.

Reviews of airlines servicing Islip

Get insights into the airlines that provide service to Islip. 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 Islip. Reviews last updated setembro 16, 2025.
Peruse reviews from past customers who have flown with Southwest from St. Louis to Islip to help guide your decision. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,242 reviews

Food

7.0

Overall

8.0

Entertainment

7.5

Comfort

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Southwest
8.0
Very good
4,242 reviews
Southwest
8.0
Very good
4,242 reviews

Food

7.0

Overall

8.0

Entertainment

7.5

Comfort

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines

Related info for your journey

Find useful and relevant information for your journey from St. Louis to Islip. 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 St. Louis to Islip?

    There are many flights that can get you from St. Louis to Islip in 4h 35m. Fly via Frontier or Southwest to get the fastest option. There are 926 mi between St. Louis and Islip. Both multi-stop and nonstop flights can be found to your destination and back.

  • What is the cheapest airline to fly from St. Louis to Islip round-trip?

    Our cheapest airline available from St. Louis to Islip is Southwest. Our recent data shows that you can find tickets from as low as $302 on this airline. This flight start at 26% lower than the current average price 3 months from now.

  • Can I find deals for flights from St. Louis to Islip that include hotel bookings?

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

  • How can I find direct flights from St. Louis to Islip?

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

  • Can I find deals for business class flights from St. Louis to Islip?

    Yes. Cheapflights offers flight deals from St. Louis to Islip 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 St. Louis to Islip?

    Currently, January is the cheapest month in which you can book a flight from St. Louis to Islip (average of $108). Flying from St. Louis to Islip in November is currently the most expensive (average of $213). 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

Traveling to a place near Islip?

Book flights to Islip if you plan to visit one of these locations
Riverhead
Southampton

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Alternative routes for St. Louis to Islip

See prices for flight routes from nearby airports that may be better suited for you.
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Top airline flying from St. Louis to Islip

Discover the top airline that operate flights from St. Louis to Islip. 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 setembro 16, 2025.
AirlineCheapestAverageFlexibilityOn-time
SouthwestCheapest$302Average$396FlexibilityNo cancel feeOn-time63%

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