ISP - STL

$103 Find Cheap Flights from Islip to St. Louis

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Islip to St. Louis departing on 10/25. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy

KAYAK searches hundreds of travel sites at once for deals on flights to St. Louis

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Islip to St. Louis, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Islip to St. Louis, as well as popular online travel agencies
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Flights Deals

Cheap Flights from Islip to St. Louis (ISP-STL)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Islip to St. Louis that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Islip to St. Louis

Tue, Sep 16 - Sat, Sep 20
Southwest Logo
6:05 am - 9:35 amISP-STL
4h 30m1 stop
Southwest Logo
12:30 pm - 9:40 pmSTL-ISP
8h 10m1 stop
$222Southwest
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Tue, Sep 16 - Sat, Sep 20
Southwest Logo
4:00 pm - 10:05 pmISP-STL
7h 05m2 stops
Southwest Logo
12:30 pm - 9:40 pmSTL-ISP
8h 10m1 stop
$228Southwest
Find Deal
Tue, Sep 16 - Sat, Sep 20
Southwest Logo
6:05 am - 1:10 pmISP-STL
8h 05m2 stops
Southwest Logo
10:30 am - 9:40 pmSTL-ISP
10h 10m2 stops
$233Southwest
Find Deal
Thu, Aug 14 - Mon, Aug 18
Frontier Logo
6:00 am - 11:47 pmISP-STL
18h 47m1 stop
Frontier Logo
5:40 pm - 11:59 pmSTL-ISP
29h 19m1 stop
$277Frontier
Find Deal
Mon, Dec 29 - Fri, Jan 2
Southwest Logo
6:00 pm - 11:30 pmISP-STL
6h 30m1 stop
Southwest Logo
5:45 am - 11:55 amSTL-ISP
5h 10m1 stop
$367Southwest
Find Deal
Mon, Dec 29 - Fri, Jan 2
Southwest Logo
5:40 am - 9:10 amISP-STL
4h 30m1 stop
Southwest Logo
2:15 pm - 11:55 pmSTL-ISP
8h 40m2 stops
$372Southwest
Find Deal
Mon, Dec 29 - Fri, Jan 2
Southwest Logo
5:40 am - 11:25 amISP-STL
6h 45m2 stops
Southwest Logo
2:15 pm - 11:55 pmSTL-ISP
8h 40m2 stops
$377Southwest
Find Deal
Booking Insights

KAYAK's insights & trends for Islip to St. Louis flights

Get data-powered insights and trends into flights from Islip to St. Louis to help you find the cheapest flights, the best time to fly and much more.

Which airlines provide the cheapest flights from Islip to St. Louis?

The cheapest round-trip price for the route for each airline clicked by KAYAK users in the last 72 hours.

In the past 3 days, the cheapest round-trip tickets from Islip to St. Louis were found on Southwest ($222) and Frontier ($277).

Good to know

Cheapest flight$103
Flight from Islip to St. Louis

When to book flights from Islip to St. Louis

Are your dates flexible? Find out the best times to travel from Islip to St. Louis based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking flights from Islip to St. Louis

  • What is the cheapest flight from Islip to St. Louis?

    In the last 3 days, the lowest price for a flight from Islip to St. Louis was $103 for a one-way ticket and $222 for a round-trip.

  • Do I need a passport to fly between Islip and St. Louis?

    A passport is not required to fly from Islip to St. Louis.

  • Which airports will I be using when flying from Islip to St. Louis?

    Islip airport is called Islip Long Island and the only airport in St. Louis is Lambert-St Louis.

  • Which aircraft models fly most regularly from Islip to St. Louis?

    We unfortunately don’t have that data for this specific route.

  • How does KAYAK find such low prices on flights from Islip to St. Louis?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Islip to St. Louis.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Islip to St. Louis?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to St. Louis from Islip is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Islip to St. Louis?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to St. Louis with an airline and back to Islip with another airline. Booking your flights between Islip and STL can sometimes prove cheaper using this method.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Islip to St. Louis?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to St. Louis from Islip up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

Reviews of the top airline flying from Islip to St. Louis

 
See real verified KAYAK customer reviews for airlines flying from Islip to St. Louis. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Islip to St. Louis? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
SouthwestOverall score based on 4241 reviews
8.0Comfort
8.1Boarding
7.0Food
8.6Crew
7.5Entertainment
Airline reviews

southwest just starting charging for luggage. hadnt realized it until it was too late. now out $70 when i couldve bought a carry on if i wouldve known. free bags was one of the only reasons i chose southwest over another airline (the other being no assigned seats, which is apparently also being changed). stupid business decision. wont be flying southwest anymore.

2.0 MediocreAnonymous, Jul 2025AUS - RDU
Read more Southwest reviews

southwest just starting charging for luggage. hadnt realized it until it was too late. now out $70 when i couldve bought a carry on if i wouldve known. free bags was one of the only reasons i chose southwest over another airline (the other being no assigned seats, which is apparently also being changed). stupid business decision. wont be flying southwest anymore.

The quality of Southwest Airlines continues to degrade each time I fly with them. If it were not for the free luggage, I would probably choose another airline. Their prices are a little bit competitive, but way too high for the quality of the service. Southwest is not unique in this way. Domestic flight in the United States of America has continued to be a lower and lower quality product. Very sad when you compare the quality of domestic airlines to that of many international airlines around the world.

Very smooth checking in our luggage with a super pleasant SW agent. I enjoyed a fun entertaining movie.

WiFi did not work. For as outrageous as these flights cost, when they’re advertised with certain services/ features they should be in working order

Worst experience I had on Southwest. Still better than most, but the seating was barely tolerable.

The Southwest employees (all two of them) were very nice and cheerful despite the fact the line to self-check a bag (simply drop it off) was hundreds of people long. Thank God I arrived early to the airport because I stood in this line for at least an hour. Once on the flight that had been delayed by an hour, we had no Wi-Fi and thus no entertainment. Finally, I hope the investor strong arm tactics against Southwest pay off in a short-term windfall to your C-Suite because the rest of you are screwed. I have been a faithful Southwest customer for 15 years due to everything you just got rid of. I'm flying to Idaho and Washington in October, both places I used to simply book with Southwest without a second thought now with Frontier (Washington) and United (Idaho) because they offer everything the "new" Southwest does but cheaper and at better times, destinations, etc. This really makes me sad...

It was okay. The plane was delayed from earlier in the day, but they kept updating the departure time, sometimes later, sometimes earlier. That was stressful. Once we finally got on and took off, it was fine. I was supposed to have a connection in Chicago to Los Angeles, and the time for so late I was rebooked to arrive in LA 3 hours late. The departure time to Chicago later became early enough to have taken my original connection and arrive earlier but that wasn't an option.

It was one and half hour late... Not sure if any other experience matters.

Delayed flight. Nicest crew member was a SW pilot flying seated next to me who kindly move to seat the final passenger. Flight extra delayed. My cup of refreshment of ginger ale was so packed with ice it was literally 2 sips.

For my birthday trip this was my second time ever flying, this trip was the best.

Everything you need to know for your flight from Islip to St. Louis

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