STL - ISP

$94 Find Cheap Flights from St. Louis to Islip

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from St. Louis to Islip departing on 10/23. 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 Islip

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

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

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from St. Louis to Islip 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 St. Louis to Islip

Mon, Sep 8 - Thu, Sep 11
Frontier Logo
1:57 pm - 10:40 amSTL-ISP
19h 43m1 stop
Frontier Logo
11:25 am - 1:02 pmISP-STL
26h 37m1 stop
$225Frontier
Find Deal
Mon, Sep 8 - Thu, Sep 11
Frontier Logo
4:00 pm - 10:40 amSTL-ISP
17h 40m2 stops
Frontier Logo
11:25 am - 1:02 pmISP-STL
26h 37m1 stop
$272Frontier
Find Deal
Mon, Sep 8 - Thu, Sep 11
Frontier Logo
4:00 pm - 10:40 amSTL-ISP
17h 40m2 stops
Frontier Logo
11:25 am - 9:06 amISP-STL
46h 41m2 stops
$343Frontier
Find Deal
Tue, Sep 9 - Tue, Sep 16
Southwest Logo
2:15 pm - 10:05 pmSTL-ISP
6h 50m1 stop
Southwest Logo
6:05 am - 9:35 amISP-STL
4h 30m1 stop
$350Southwest
Find Deal
Tue, Sep 9 - Tue, Sep 16
Southwest Logo
5:25 am - 3:15 pmSTL-ISP
8h 50m2 stops
Southwest Logo
6:05 am - 9:35 amISP-STL
4h 30m1 stop
$355Southwest
Find Deal
Sun, Sep 14 - Fri, Sep 19
 Logo
1:52 pm - 10:40 amSTL-ISP
19h 48m1 stop
 Logo
5:12 pm - 9:40 amISP-STL
41h 28m2 stops
Thu, Sep 18 - Sun, Sep 21
Frontier Logo
4:00 pm - 4:23 pmSTL-ISP
47h 23m2 stops
Frontier Logo
5:12 pm - 3:04 pmISP-STL
22h 52m2 stops
$380Frontier
Find Deal
Tue, Sep 9 - Tue, Sep 16
Southwest Logo
5:25 am - 3:15 pmSTL-ISP
8h 50m2 stops
Southwest Logo
6:05 am - 1:10 pmISP-STL
8h 05m2 stops
$384Southwest
Find Deal
Thu, Sep 18 - Sun, Sep 21
Southwest Logo
4:15 pm - 10:55 pmSTL-ISP
5h 40m1 stop
Southwest Logo
6:50 pm - 11:55 pmISP-STL
6h 05m1 stop
$387Southwest
Find Deal
Thu, Sep 18 - Sun, Sep 21
Frontier Logo
4:00 pm - 10:55 amSTL-ISP
41h 55m2 stops
Frontier Logo
11:25 am - 1:02 pmISP-STL
26h 37m1 stop
$395Frontier
Find Deal
Booking Insights

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

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

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

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 St. Louis to Islip were found on Frontier ($225) and Southwest ($350).

Good to know

Low seasonApril
Cheapest flight$94
Best time to beat the crowds with an average 26% drop in price.
Most popular time to fly and prices are also 1% lower on average.
Flight from St. Louis to Islip

When to book flights from St. Louis to Islip

Are your dates flexible? Find out the best times to travel from St. Louis to Islip 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 St. Louis to Islip

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

    In the last 3 days, the lowest price for a flight from St. Louis to Islip was $94 for a one-way ticket and $225 for a round-trip.

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

    No, a passport isn't needed to fly from St. Louis to Islip. However, local authorities might ask for an official ID.

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

    When flying out of St. Louis you will be using Lambert-St Louis. You will be landing at Islip, also known as Islip Long Island.

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

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

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

    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 St. Louis to Islip.

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Islip from St. Louis 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 St. Louis to Islip?

    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 Islip with an airline and back to St. Louis with another airline. Booking your flights between St. Louis and ISP 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 St. Louis to Islip?

    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 Islip from St. Louis 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 St. Louis to Islip

 
See real verified KAYAK customer reviews for airlines flying from St. Louis to Islip. 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 St. Louis to Islip? 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
8.6Crew
7.0Food
8.0Comfort
7.5Entertainment
8.1Boarding
Airline reviews

AC sub par. WiFi not working correctly. Ac sucked. Seats very narrow.

2.0 MediocreMike, Aug 2025AUS - BWI
Read more Southwest reviews

AC sub par. WiFi not working correctly. Ac sucked. Seats very narrow.

Near 4 hour flight with only 1 service. Had to use call button to request water. Internet and power not working until into flight. Internet would stop working during flight.

Southwest's seats are the least comfortable I have ever sat in.

The cabin was quiet for the redeye flight. The area was clean. The staff was great. The 787 Max was in good condition. Drawbacks were that the seat widths were tight for some passengers. The seat padding was at best average and for a long flight uncomfortable.

Southwest like most American domestic airlines, is a mediocre airline. But it is among the cheapest. Oh well.

My flight was delayed 50 minutes and we were rushed to board to then sit for 15 minutes until the pilot arrived. Unacceptable since we could have waited to board. Also the delayed flight was updated AFTER we boarded to more than the 10 minutes as originally stated.

Other than a bit of a delay, everything was good. Again, the boarding process and picking seats is the only thing I don't enjoy.

If we are going to have to pay for luggage, make it easier to do. Put something on the app during check-in so I don't need to do it at the kiosk. I've done it twice recently and I ended up having to pay at the desk because something went wrong at the kiosk in Tampa.

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.

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

Information on your arrival and departure airports

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