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St. Louis

$135+ 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 1/9. Fares are subject to change and may not be available on all flights or dates of travel.
ISP — STL
ene. 3 — ene. 101
sáb. 1/3
sáb. 1/10
1 adult, Economy
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Cheap flight deals from Islip to St. Louis

Cheapest flights from Islip to St. Louis
Explore the most affordable flight options available from Islip to St. Louis. Find the lowest fares from popular airlines and budget airlines, with prices last updated on diciembre 4, 2025.

This Frontier deal was found by Cheapflights users on 12/3. 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.
jue. 12/1812:20 pmISP - STL
1 stop11h 13mFrontier
lun. 12/2210:40 amSTL - ISP
1 stop8h 00mFrontier
Deal found 12/3$234
This Southwest deal was found by Cheapflights users on 12/3. 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.
dom. 12/216:00 pmISP - STL
1 stop6h 30mSouthwest
vie. 12/265:45 amSTL - ISP
1 stop5h 10mSouthwest
Deal found 12/3$460

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 diciembre 4, 2025.

Most accurate provider

eDreams
3 stars

Most trusted provider

eDreams
3 stars

Round-trip from

$162
(Frontier)

One-way from

$135
(Southwest)

Popular in

November

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. 18% potential increase in price ($74 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($11 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 diciembre 4, 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

jue. 1/8

8:40 pm-7:50 am

1 stop12h 10m

Lambert-St Louis

lun. 1/12

8:50 am-7:51 pm

1 stop10h 01m

$162

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

vie. 3/6

5:15 pm-12:40 am

1 stop8h 25m

Lambert-St Louis

lun. 3/9

2:15 pm-11:55 pm

2 stops8h 40m

$345

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

lun. 4/6

6:00 am-10:50 am

1 stop5h 50m

Lambert-St Louis

lun. 4/6

4:45 pm-11:55 pm

1 stop6h 10m

$377

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

dom. 12/21

6:00 pm-11:30 pm

1 stop6h 30m

Lambert-St Louis

vie. 12/26

5:45 am-11:55 am

1 stop5h 10m

$460

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

vie. 3/6

8:19 pm-7:13 am

1 stop11h 54m

Lambert-St Louis

dom. 3/8

6:00 am-7:11 pm

1 stop12h 11m

$701

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

vie. 1/9

12:40 pm-7:00 pm

1 stop7h 20m

$135

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

vie. 1/9

2:01 pm-10:02 am

2 stops21h 01m

$149

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

lun. 12/29

2:04 pm-10:33 pm

1 stop9h 29m

$535

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/3

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 February is currently the most expensive (average of $226). 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 diciembre 4, 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 diciembre 4, 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
8.0
Very good
4,250 reviews

Boarding

8.1

Entertainment

7.5

Food

7.0

Comfort

8.0

Crew

8.6

Overall

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
8.0
Very good
4,250 reviews
Southwest
8.0
Very good
4,250 reviews

Boarding

8.1

Entertainment

7.5

Food

7.0

Comfort

8.0

Crew

8.6

Overall

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 8h 25m. The time it takes to get you to your destination can typically vary by up to 3h 45m. 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 February is currently the most expensive (average of $226). 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

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Alternative routes for Islip to St. Louis

See prices for flight routes from nearby airports that may be better suited for you.
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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 diciembre 4, 2025.
AirlineCheapestAverageFlexibilityOn-time
SouthwestCheapest$259Average$386FlexibilityNo cancel feeOn-time63%

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