HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
St. Louis

$122+ Cheap flights from Islip, NY to St. Louis (ISP - STL)

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 1/11. Fares are subject to change and may not be available on all flights or dates of travel.
ISP — STL
Jan 17 — Jan 241
Sat 1/17
Sat 1/24
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from Islip to St. Louis with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.

Cheap flight deals from Islip to St. Louis

Best flights from Islip to St. Louis
Discover carefully curated flight deals from Islip to St. Louis that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated December 18, 2025.

This Kiwi.com deal was found by Cheapflights users on 12/17. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 1/2012:00 pmISP - STL
2 stops19h 51mFrontier
Thu 1/225:42 pmSTL - ISP
1 stop26h 05mFrontier
Deal found 12/17$185
This Southwest deal was found by Cheapflights users on 12/16. 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.
Tue 1/63:45 pmISP - STL
2 stops7h 10mSouthwest
Mon 1/122:35 pmSTL - ISP
1 stop6h 20mSouthwest
Deal found 12/16$247
This Kiwi.com deal was found by Cheapflights users on 12/17. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 1/309:43 pmISP - STL
1 stop14h 28mMultiple Airlines
Sun 2/15:42 pmSTL - ISP
2 stops18h 39mMultiple Airlines
Deal found 12/17$277
This Priceline deal was found by Cheapflights users on 12/16. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 1/612:55 pmISP - STL
1 stop10h 38mFrontier
Mon 1/128:50 amSTL - ISP
1 stop10h 01mFrontier
Deal found 12/16$207
This Southwest deal was found by Cheapflights users on 12/17. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 1/2012:40 pmISP - STL
2 stops7h 20mSouthwest
Thu 1/226:05 amSTL - ISP
2 stops9h 10mSouthwest
Deal found 12/17$252
This Expedia deal was found by Cheapflights users on 12/17. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 1/112:20 pmISP - STL
1 stop11h 13mFrontier
Sun 1/44:27 pmSTL - ISP
1 stop19h 42mFrontier
Deal found 12/17$313
This Southwest deal was found by Cheapflights users on 12/17. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 1/3012:40 pmISP - STL
1 stop7h 20mSouthwest
Sun 2/15:05 amSTL - ISP
1 stop5h 50mSouthwest
Deal found 12/17$340
This Frontier deal was found by Cheapflights users on 12/16. 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 1/112:20 pmISP - STL
1 stop11h 13mFrontier
Mon 1/510:40 amSTL - ISP
1 stop7h 59mFrontier
Deal found 12/16$393
This Southwest deal was found by Cheapflights users on 12/17. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 1/15:40 amISP - STL
2 stops9h 10mSouthwest
Sun 1/45:45 amSTL - ISP
1 stop5h 10mSouthwest
Deal found 12/17$419

Find flight deals from Islip to St. Louis

Discover tips and strategies to find the most affordable flight options for your journey from Islip (ISP) to St. Louis (STL). 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 December 18, 2025.

Most accurate provider

eDreams
3 stars

Most trusted provider

eDreams
3 stars

Round-trip from

$185
(Kiwi.com)

One-way from

$122
(Frontier)

Popular in

December

Cheapest in

March

Average price

$439
Provider with most accurate pricing for Islip Long Island-Lambert-St Louis flight deals.
Search Deals
Provider most trusted by Cheapflights users for Islip Long Island-Lambert-St Louis flights.
Search Deals
From Islip Long Island to Lambert-St Louis
Search Deals
One-way flight from Islip Long Island to Lambert-St Louis
Search Deals
Highest demand for flights based on searches. 12% potential increase in price ($50 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($10 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Islip to St. Louis 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 December 18, 2025.
Use the filters below to find and compare flights from Islip to St. Louis that are best for you.

Fly from

Islip

Fly to

St. Louis

Route

Depart

Return

Price

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Tue 1/20

12:00 pm-6:51 am

2 stops19h 51m

Lambert-St Louis

Thu 1/22

5:42 pm-8:47 pm

1 stop26h 05m

$185

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Tue 1/6

12:55 pm-10:33 pm

1 stop10h 38m

Lambert-St Louis

Mon 1/12

8:50 am-7:51 pm

1 stop10h 01m

$207

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Tue 1/6

3:45 pm-9:55 pm

2 stops7h 10m

Lambert-St Louis

Mon 1/12

2:35 pm-9:55 pm

1 stop6h 20m

$247

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Tue 1/20

12:40 pm-7:00 pm

2 stops7h 20m

Lambert-St Louis

Thu 1/22

6:05 am-4:15 pm

2 stops9h 10m

$252

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 1/30

9:43 pm-11:11 am

1 stop14h 28m

Lambert-St Louis

Sun 2/1

5:42 pm-1:21 pm

2 stops18h 39m

$277

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 1/1

12:20 pm-10:33 pm

1 stop11h 13m

Lambert-St Louis

Sun 1/4

4:27 pm-1:09 pm

1 stop19h 42m

$313

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 1/30

12:40 pm-7:00 pm

1 stop7h 20m

Lambert-St Louis

Sun 2/1

5:05 am-11:55 am

1 stop5h 50m

$340

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 1/1

12:20 pm-10:33 pm

1 stop11h 13m

Lambert-St Louis

Mon 1/5

10:40 am-7:39 pm

1 stop7h 59m

$393

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 1/1

5:40 am-1:50 pm

2 stops9h 10m

Lambert-St Louis

Sun 1/4

5:45 am-11:55 am

1 stop5h 10m

$419

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Sun 1/11

8:40 pm-8:05 am

1 stop12h 25m

$122

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/16

Showing 1-10 of 14 results
1
2

Compare providers for flights from Islip to St. Louis

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 St. Louis in December.
ProviderPrice AccuracyTrust Score*
FlightHubPrice Accuracy3 starsTrust Score*1 star
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-St. Louis 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-St. Louis flight deals on Cheapflights vs. eDreams >95% of the time. Price accuracy is based on data collected from Islip, New York-St. Louis flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Islip, New York-St. Louis 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-St. Louis 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 St. Louis

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

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

Currently, March is the cheapest month in which you can book a flight from Islip, New York to St. Louis (average of $60). Flying from Islip, New York to St. Louis in December is currently the most expensive (average of $259). 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 ISP to STL?

Find hourly flight availability from Islip to St. Louis. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated December 18, 2025.

Unlike in the afternoon, when flights are generally more expensive, you can save up to 42% on flights from Islip, New York to St. Louis by exploring options for tickets in the evening.

Reviews of airlines servicing St. Louis

Get insights into the airlines that provide service to St. Louis. 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 St. Louis. Reviews last updated December 18, 2025.
Read reviews from past customers who have flown Southwest from Islip to St. Louis. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
7.9
Good
4,250 reviews

Crew

8.6

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Southwest
7.9
Good
4,250 reviews
Southwest
7.9
Good
4,250 reviews

Crew

8.6

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

Related info for your journey

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

    Airlines like Frontier and Southwest fly from Islip, New York to St. Louis in about 7h 10m. The time it takes to get you to your destination can typically vary by up to 12h 41m. Islip, New York and St. Louis are separated by a distance of 926 mi. This flight may include one or multiple stops.

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

    According to our current data, Southwest ($259), offers the cheapest pricing from Islip, New York to St. Louis.

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

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

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

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

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

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

    Currently, March is the cheapest month in which you can book a flight from Islip, New York to St. Louis (average of $60). Flying from Islip, New York to St. Louis in December is currently the most expensive (average of $259). 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 St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
Edwardsville
O'Fallon
Fairview Heights
Maryland Heights
Collinsville
Swansea
Eureka
Glencoe
St. Peters
Chesterfield
Alton
Farmington
Festus

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Islip to St. Louis

See prices for flight routes from nearby airports that may be better suited for you.
John F Kennedy Intl to Kansas City flights
Newark to St. Louis flights
LaGuardia to Kansas City flights
John F Kennedy Intl to St. Louis flights
LaGuardia to St. Louis flights
Newark to Kansas City flights
Newark to Springfield flights
Syracuse to Kansas City flights
John F Kennedy Intl to Springfield flights
LaGuardia to Springfield flights
Albany to St. Louis flights
Albany to Kansas City flights
Syracuse to St. Louis flights
Rochester to Columbia flights
Rochester to Kansas City flights
White Plains to St. Louis flights
Rochester to St. Louis flights
Syracuse to Springfield flights
Albany to Springfield flights
Buffalo to St. Louis flights
Buffalo to Springfield flights
Stewart to Kansas City flights
Rochester to Springfield flights
Buffalo to Kansas City flights
Syracuse to Columbia flights
White Plains to Kansas City flights
Newark to Columbia flights
Ithaca to Kansas City flights
Ithaca to St. Louis flights
Buffalo to Columbia flights
LaGuardia to Columbia flights
Newark to Joplin flights
Islip to Kansas City flights
John F Kennedy Intl to Columbia flights
White Plains to Springfield flights
Stewart to St. Louis flights
LaGuardia to Joplin flights
Albany to Joplin flights
Elmira to Kansas City flights
Binghamton to St. Louis flights
Binghamton to Kansas City flights
Watertown to Kansas City flights
Stewart to Columbia flights
Watertown to St. Louis flights
White Plains to Columbia flights

Top airline flying from Islip to St. Louis

Discover the top airline that operate flights from Islip to St. Louis. 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 December 18, 2025.
AirlineCheapestAverageFlexibilityOn-time
SouthwestCheapest$259Average$383FlexibilityNo cancel feeOn-time63%

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.