ISP - STL

$292 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 12/22. 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, 0 bags

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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Everything you should know

Cheapest round-trip
$292
Frontier
Mon 1/5Mon 1/12
ISP - STL • 1 stop
Cheapest one-way
$161
Frontier
Mon 12/22
ISP - STL • 1 stop
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We hope you love your trip to St. Louis!
Flight Deals
Booking Insights
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, Jan 5 - Mon, Jan 12
Frontier Logo
2:04 pm - 10:33 pm
ISP
-
STL
9h 29m1 stop
Frontier Logo
8:50 am - 7:51 pm
STL
-
ISP
10h 01m1 stop
$292Frontier
Mon, Jan 5 - Sun, Jan 11
Frontier Logo
2:04 pm - 10:33 pm
ISP
-
STL
9h 29m1 stop
Frontier Logo
9:35 am - 7:45 pm
STL
-
ISP
9h 10m1 stop
$327Frontier
Sat, Dec 27 - Wed, Dec 31
Frontier Logo
6:40 pm - 9:40 am
ISP
-
STL
16h 00m2 stops
Frontier Logo
4:27 pm - 11:25 am
STL
-
ISP
17h 58m1 stop
$798Frontier
Sat, Dec 27 - Wed, Dec 31
Frontier Logo
6:40 pm - 10:33 pm
ISP
-
STL
28h 53m1 stop
Frontier Logo
4:27 pm - 11:25 am
STL
-
ISP
17h 58m1 stop
$863Frontier
Thu, Mar 26 - Sun, Mar 29
Frontier Logo
5:08 pm - 11:19 pm
ISP
-
STL
7h 11m1 stop
Frontier Logo
7:52 am - 4:13 pm
STL
-
ISP
7h 21m1 stop
$870Frontier
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 fly non-stop between Islip and St. Louis?

Airline and price data is aggregated from results in KAYAK’s search results from the last 2 weeks for round-trip flights from Islip to St. Louis.

There is just one airline that flies from Islip to St. Louis direct and that is Southwest. The best round-trip deal found from Southwest for the route is $259.

Find deals

Good to know

Cheapest flight$161
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 $161 for a one-way ticket and $292 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.
7.9
SouthwestOverall score based on 4250 reviews
8.1Boarding
7.5Entertainment
8.6Crew
8.0Comfort
7.0Food
Airline reviews

The boarding and seat assignment system no longer works for me, but I know it is being replaced. Otherwise, I am good with the overall experience.

8.0 ExcellentRussell, Dec 2025
SAN - OAK
Read more Southwest reviews

The boarding and seat assignment system no longer works for me, but I know it is being replaced. Otherwise, I am good with the overall experience.

The lead steward kept singing about "San Francisco" and hotel California---more annoying than humorous....needs work. Flight was smooth and on time.

Still a fan of open seating. Flight was on schedule and arrived on time. The 737 MAX is very comfortable.

Airline travel is always too cramped to really be pleasant, but the cabin crew on this flight did a pretty good job of making up for it by putting on some music during boarding and sprinkling a few funny remarks into the safety briefing and announcements, and just generally being friendly and helpful. It definitely reminded me of why I prefer the in-flight experience on Southwest!

No delays and arrived to destination 30 min early. Staff was super friendly.

San Diego airport is brand new, spacious, airy and very smooth checkin at SW baggage drop.

It was rough. The staff was unprofessional, the choice of on board drinks terrible, it was cramped in space at every airport, they always ran out of overhead bin space so they pressured people to check bags for free or we couldn’t leave on the plane— so I did check my bag to help, and they nearly lost my bag. My bag did not arrive on the luggage belt, another man on my flight and I had to waste our time going to the baggage office to search for our bags. I would only fly southwest again if it was my last choice. Also, my flights were consistently delayed over and over again— at one point they straight up told us we were waiting for the pilot to arrive.

Crew could have been friendlier, maybe I'm spoiled by SW crews. In flight wifi was good. Would be nice to have more food offerings on a 4 plus hour flight

Had to get off plane from prior flight even though I had to reboard same plane to continue to my final destination.

Everything a cheap airline should be at normal airline rates.

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

Information on your arrival and departure airports

Islip (ISP)
St. Louis (STL)