ISP - STL

$80 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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Flight 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

Mon, Sep 29 - Fri, Oct 3
Frontier Logo
5:05 pm - 9:06 amISP-STL
17h 01m2 stops
Frontier Logo
9:32 pm - 10:55 amSTL-ISP
12h 23m1 stop
$202Frontier
Find Deal
Thu, Oct 2 - Sun, Oct 5
Frontier Logo
11:40 am - 9:06 amISP-STL
22h 26m2 stops
Frontier Logo
10:39 am - 10:40 amSTL-ISP
23h 01m2 stops
$237Frontier
Find Deal
Thu, Oct 2 - Sun, Oct 5
Frontier Logo
11:40 am - 9:06 amISP-STL
22h 26m2 stops
Frontier Logo
10:39 am - 10:40 amSTL-ISP
23h 01m2 stops
$238Frontier
Find Deal
Thu, Oct 2 - Sat, Oct 4
Frontier Logo
11:40 am - 9:06 amISP-STL
22h 26m2 stops
Frontier Logo
7:55 pm - 9:04 amSTL-ISP
12h 09m2 stops
$246Frontier
Find Deal
Sat, Oct 4 - Sun, Oct 5
Frontier Logo
5:05 pm - 9:06 amISP-STL
17h 01m2 stops
Frontier Logo
7:55 pm - 10:40 amSTL-ISP
13h 45m2 stops
$280Frontier
Find Deal
Tue, Nov 25 - Fri, Nov 28
Southwest Logo
1:35 pm - 9:50 pmISP-STL
9h 15m1 stop
Southwest Logo
5:05 pm - 11:50 pmSTL-ISP
5h 45m1 stop
$297Southwest
Find Deal
Tue, Nov 25 - Fri, Nov 28
Southwest Logo
1:35 pm - 9:50 pmISP-STL
9h 15m1 stop
Southwest Logo
2:30 pm - 11:50 pmSTL-ISP
8h 20m2 stops
$302Southwest
Find Deal
Thu, Nov 27 - Tue, Dec 2
Southwest Logo
6:00 am - 9:50 amISP-STL
4h 50m1 stop
Southwest Logo
6:05 am - 3:20 pmSTL-ISP
8h 15m1 stop
$310Southwest
Find Deal
Thu, Nov 27 - Tue, Dec 2
Southwest Logo
6:00 am - 9:50 amISP-STL
4h 50m1 stop
Southwest Logo
12:45 pm - 10:05 pmSTL-ISP
8h 20m2 stops
$333Southwest
Find Deal
Fri, Nov 28 - Mon, Dec 1
Multiple Airlines Logo
11:32 am - 11:57 pmISP-STL
13h 25m1 stop
Multiple Airlines Logo
7:03 pm - 7:14 pmSTL-ISP
23h 11m2 stops
$853Multiple Airlines
Find Deal

Everything you should know

Top airlines
Frontier
Cheapest • from $202 (round-trip)
Southwest
Best reviews • 8.0 score
Airline reviews
Airline reviews
+1
+1
Airline reviews
Airline reviews
+1
Cheapest round-trip
$202
Typical prices: $349-351
Frontier
Mon 9/29Fri 10/3
ISP - STL • 2 stops
Cheapest one-way
$80
Frontier
Sat 10/25
ISP - STL • 1 stop
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KAYAK searches 100s of sites at once to find you the best travel deals.
We hope you love your trip to St. Louis!
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 Frontier ($202) and Southwest ($297).

Good to know

Low seasonJuly
Cheapest flight$80
Best time to beat the crowds with an average 35% drop in price.
Most popular time to fly and prices are also 11% lower on average.
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 $80 for a one-way ticket and $202 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 4242 reviews
8.1Boarding
8.6Crew
7.5Entertainment
7.0Food
8.0Comfort
Airline reviews

I wish they had movie screens in the headrests. The seats are much improved, more legroom and recently renovated. Bathroom was clean. Staff was outstanding!!

10.0 ExcellentG, Sep 2025LAS - ATL
Read more Southwest reviews

I wish they had movie screens in the headrests. The seats are much improved, more legroom and recently renovated. Bathroom was clean. Staff was outstanding!!

As always, the entire Southwest experience was wonderful, from online booking to flight to baggage retrieval. Very grateful.

The weather could have been better. There was a 40 minute ATC delay in SFO because of marine fog and a micro cell storm delayed landing and take-off at Nashville. The gate was changed 5 minutes from boarding from gate B3 to gate C23 at Nashville airport.

After being assaulted by a flight attendant I was then brushed off as oh well because he long braids didn’t mean to whip me in the eye. I have filed complaints and will see. But like any other issue I’ve had with kayak involved it’s been trash. Last time I’ll be using your app

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.

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

Information on your arrival and departure airports

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