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Cheap flights from Islip, New York to St. Louis from $247

This is the cheapest round-trip flight price found by a momondo user in the last 72 hours by searching for a flight from Islip, New York to St. Louis departing on 9/30. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
1 adult
1 adult, Economy, 0 bags

Find the cheapest flights from Islip, New York to St. Louis

Cheap round-trip flights

Enter your travel dates to find the best prices.
Southwest Logo
6:05 am - 10:05 am
ISP
-
STL
5h 00m
1 stop
Southwest Logo
6:45 am - 2:30 pm
STL
-
ISP
6h 45m
1 stop
$247Southwest
Wed, Sep 30 - Mon, Oct 5
Southwest Logo
12:55 pm - 5:55 pm
ISP
-
STL
6h 00m
2 stops
Southwest Logo
5:40 pm - 11:35 pm
STL
-
ISP
4h 55m
1 stop
$252Southwest
Wed, Sep 30 - Mon, Oct 5
Southwest Logo
3:20 pm - 10:10 pm
ISP
-
STL
7h 50m
2 stops
Southwest Logo
4:30 pm - 11:35 pm
STL
-
ISP
6h 05m
2 stops
$257Southwest
Wed, Sep 30 - Mon, Oct 5
Southwest Logo
12:35 pm - 6:25 pm
ISP
-
STL
6h 50m
1 stop
Southwest Logo
4:15 pm - 10:05 pm
STL
-
ISP
4h 50m
1 stop
$272Southwest
Fri, Aug 7 - Fri, Aug 14
Southwest Logo
4:05 pm - 9:40 pm
ISP
-
STL
6h 35m
1 stop
Southwest Logo
2:45 pm - 10:05 pm
STL
-
ISP
6h 20m
2 stops
$278Southwest
Fri, Aug 7 - Fri, Aug 14
Southwest Logo
6:10 am - 11:35 am
ISP
-
STL
6h 25m
1 stop
Southwest Logo
6:05 am - 12:35 pm
STL
-
ISP
5h 30m
1 stop
$321Southwest
Mon, Aug 10 - Mon, Aug 17
Southwest Logo
4:05 pm - 10:05 pm
ISP
-
STL
7h 00m
2 stops
Southwest Logo
2:45 pm - 10:05 pm
STL
-
ISP
6h 20m
2 stops
$339Southwest
Fri, Aug 7 - Fri, Aug 14
Southwest Logo
6:10 am - 11:35 am
ISP
-
STL
6h 25m
1 stop
Southwest Logo
2:45 pm - 10:05 pm
STL
-
ISP
6h 20m
2 stops
$365Southwest
Mon, Aug 10 - Mon, Aug 17
Southwest Logo
4:05 pm - 10:05 pm
ISP
-
STL
7h 00m
2 stops
Southwest Logo
2:45 pm - 10:05 pm
STL
-
ISP
6h 20m
2 stops
$477Southwest
Mon, Aug 10 - Mon, Aug 17
Frontier Logo
10:57 am - 11:59 pm
ISP
-
STL
14h 02m
1 stop
Frontier Logo
4:09 pm - 9:53 am
STL
-
ISP
16h 44m
1 stop
$487Frontier
Mon, Jul 27 - Fri, Jul 31

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Southwest flights from Islip, New York to St. Louis

Our best Southwest deals on Islip, New York to St. Louis flight tickets
Southwest
Sep 30
ISP6:05 amIslip Long Island
5h 00m
1 stop
STL10:05 amLambert-St Louis
Oct 5
STL6:45 amLambert-St Louis
6h 45m
1 stop
ISP2:30 pmIslip Long Island
$247
Southwest
Sep 30
ISP12:55 pmIslip Long Island
6h 00m
2 stops
STL5:55 pmLambert-St Louis
Oct 5
STL5:40 pmLambert-St Louis
4h 55m
1 stop
ISP11:35 pmIslip Long Island
$252
Southwest
Sep 30
ISP3:20 pmIslip Long Island
7h 50m
2 stops
STL10:10 pmLambert-St Louis
Oct 5
STL4:30 pmLambert-St Louis
6h 05m
2 stops
ISP11:35 pmIslip Long Island
$257

momondo Fare Finder

 
Customize your flight search to find flights from Islip, New York 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, momondo users made 832,500 searches. Data last updated July 13, 2026.
Use the filters below to find and compare flights from Islip, New York to St. Louis that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 9/30

6:05 am-10:05 am

1 stop5h 00m

Lambert-St Louis

Mon 10/5

6:45 am-2:30 pm

1 stop6h 45m

$247
Quickest round-trip

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 9/30

12:55 pm-5:55 pm

2 stops6h 00m

Lambert-St Louis

Mon 10/5

5:40 pm-11:35 pm

1 stop4h 55m

$252

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 9/30

3:20 pm-10:10 pm

2 stops7h 50m

Lambert-St Louis

Mon 10/5

4:30 pm-11:35 pm

2 stops6h 05m

$257

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 8/7

12:35 pm-6:25 pm

1 stop6h 50m

Lambert-St Louis

Fri 8/14

4:15 pm-10:05 pm

1 stop4h 50m

$272

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 8/7

4:05 pm-9:40 pm

1 stop6h 35m

Lambert-St Louis

Fri 8/14

2:45 pm-10:05 pm

2 stops6h 20m

$278

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 8/10

6:10 am-11:35 am

1 stop6h 25m

Lambert-St Louis

Mon 8/17

6:05 am-12:35 pm

1 stop5h 30m

$321

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 8/7

4:05 pm-10:05 pm

2 stops7h 00m

Lambert-St Louis

Fri 8/14

2:45 pm-10:05 pm

2 stops6h 20m

$339

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 8/10

6:10 am-11:35 am

1 stop6h 25m

Lambert-St Louis

Mon 8/17

2:45 pm-10:05 pm

2 stops6h 20m

$365

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 8/10

4:05 pm-10:05 pm

2 stops7h 00m

Lambert-St Louis

Mon 8/17

2:45 pm-10:05 pm

2 stops6h 20m

$477

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 7/27

10:57 am-11:59 pm

1 stop14h 02m

Lambert-St Louis

Fri 7/31

4:09 pm-9:53 am

1 stop16h 44m

$487

Flights are sorted by cheapest round-trip flights first.

Sorted by cheapest first

See travel insights to St. Louis from

How to get the cheapest flight ticket from Islip, New York to St. Louis

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

What is the cheapest day to depart on your flight to St. Louis?

The cheapest day to depart on your flight to St. Louis is on a Wednesday when prices can be found for as low as $374. This is often the case because there is less demand to fly during this day of the week. If your travel schedule is flexible, try to avoid departing on a Sunday because tickets tend to average around $487. These prices are subject to change though, so be sure to set up a Price Alert for flights to St. Louis.

What is the cheapest time of day to depart on your flight to St. Louis?

Flying to St. Louis from Islip, New York in the evening is the least expensive time of day to depart. momondo users have found prices as low as $386 when looking at flights departing in the evening. At noon is when there is more demand to fly to St. Louis, so prices are often more expensive at around $419 per ticket.

When to book flights from Islip, New York to St. Louis

Are you open to changing your travel dates? Check out the ideal times to fly from Islip, New York to St. Louis according to our flight data. Find out which month and days have the cheapest flights.
Estimated round-trip price

Cheap Islip, New York to St. Louis (ISP to STL) flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Islip, New York to St. Louis

Fastest flight time

6h 15m

Direct flights

None
The fastest flight from Islip, New York to St. Louis takes 6h 15m
There are no direct flights from Islip, New York to St. Louis. There are no popular flight routes from Islip, New York to St. Louis.
Search flight deals

Frequently asked questions about flying from Islip, New York to St. Louis

  • How far is Islip Long Island to Lambert-St Louis by plane?

    There are 912.8 mi between Islip Long Island and Lambert-St Louis. In terms of flight time, this usually takes a little over 6h 15m.

  • When did momondo last update prices for flights from Islip Long Island Airport to Lambert-St Louis Airport?

    Prices for flights from Islip Long Island Airport to Lambert-St Louis Airport are refreshed on a daily basis.

  • How old do you have to be to fly from Islip Long Island Airport to Lambert-St Louis Airport?

    The minimum age for a child to fly alone is five, but airlines that offer an unaccompanied minor (UNMR) service may have their own age limitations. Flight duration, scheduling, and layovers are among the considerations that may influence age limits. We recommend that you double-check with the airline you are booking with for travel from Islip Long Island Airport to Lambert-St Louis Airport.

  • What documentation or ID do you need to fly to Lambert-St Louis Airport?

    The travel and health documents you'll need for your trip to Lambert-St Louis Airport may differ based on your itinerary and personal situation. Typically, you should have several documents on hand, such as a national ID card or driver's license and a passport that is valid for six months after your intended arrival at Lambert-St Louis Airport. It is always advisable to seek advice from your airline or a trusted third party, such as IATA.

Traveling to a place near St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
St. Charles
Chesterfield
Fairview Heights
Hermann
Collinsville
Florissant
St. Peters
Maryland Heights
O'Fallon
Alton
Farmington
Wentzville
Clayton
Fenton
Festus
Eureka
Edwardsville
Litchfield
Grafton
Shrewsbury

Why use momondo?

Why should I use momondo to find a flight deal from Islip to St. Louis?

momondo compares prices from hundreds of airlines and agents so you can find and book the best deal on flights from Islip to St. Louis. Millions of users trust and use momondo every year so you are in good hands.

Can I find flights from Islip to St. Louis with flexible booking policies on momondo?

Yes. momondo allows you to filter the results for Islip to St. Louis flights to just show those with flexible booking policies.

How can momondo help me find flights from Islip to St. Louis?

momondo offers useful filters to help you find the right flight. Choose specific flight times, airports or even what payment method you prefer. We have numerous options to help you book your ideal flight from Islip to St. Louis.

I’m not ready to book a flight from Islip to St. Louis right now. Can momondo alert me if prices change?

Price alerts on flights to St. Louis from Islip are quick and easy to set up on momondo. Simply perform a search and select the price alert feature. It is as simple as that.

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