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Cheap flights from Islip, New York to St. Louis from $90

This is the cheapest one-way 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 4/13. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
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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
4:30 pm - 11:25 pm
ISP
-
STL
7h 55m
1 stop
Southwest Logo
4:00 pm - 11:30 pm
STL
-
ISP
6h 30m
1 stop
$276Southwest
Thu, Apr 23 - Mon, Apr 27
Frontier Logo
1:22 pm - 7:25 pm
ISP
-
STL
7h 03m
1 stop
Frontier Logo
8:02 am - 4:13 pm
STL
-
ISP
7h 11m
1 stop
$290Frontier
Mon, Mar 23 - Thu, Mar 26
Southwest Logo
5:55 pm - 11:05 pm
ISP
-
STL
6h 10m
1 stop
Southwest Logo
5:20 am - 11:40 am
STL
-
ISP
5h 20m
1 stop
$314Southwest
Mon, Mar 30 - Mon, Apr 6
Southwest Logo
4:30 pm - 11:40 pm
ISP
-
STL
8h 10m
2 stops
Southwest Logo
4:00 pm - 11:30 pm
STL
-
ISP
6h 30m
1 stop
$319Southwest
Thu, Apr 23 - Mon, Apr 27
Southwest Logo
6:05 am - 10:05 am
ISP
-
STL
5h 00m
1 stop
Southwest Logo
6:45 am - 12:05 pm
STL
-
ISP
4h 20m
1 stop
$340Southwest
Tue, Sep 1 - Sat, Sep 5
Southwest Logo
10:55 am - 2:50 pm
ISP
-
STL
4h 55m
1 stop
Southwest Logo
5:45 am - 2:30 pm
STL
-
ISP
7h 45m
2 stops
$345Southwest
Tue, Sep 1 - Sat, Sep 5
Southwest Logo
6:05 am - 12:10 pm
ISP
-
STL
7h 05m
2 stops
Southwest Logo
5:45 am - 2:30 pm
STL
-
ISP
7h 45m
2 stops
$350Southwest
Tue, Sep 1 - Sat, Sep 5
Southwest Logo
8:35 am - 3:25 pm
ISP
-
STL
7h 50m
2 stops
Southwest Logo
6:50 pm - 11:50 pm
STL
-
ISP
4h 00m
1 stop
$362Southwest
Thu, Apr 23 - Sun, Apr 26
Southwest Logo
8:35 am - 3:25 pm
ISP
-
STL
7h 50m
2 stops
Southwest Logo
2:10 pm - 11:30 pm
STL
-
ISP
8h 20m
2 stops
$377Southwest
Thu, Apr 23 - Mon, Apr 27
Southwest Logo
5:15 pm - 12:40 am
ISP
-
STL
8h 25m
1 stop
Southwest Logo
4:45 pm - 11:55 pm
STL
-
ISP
6h 10m
1 stop
$391Southwest
Mon, Mar 23 - Fri, Mar 27

Southwest flights from Islip, New York to St. Louis

Our best Southwest deals on Islip, New York to St. Louis flight tickets
Southwest
Apr 23
ISP4:30 pmIslip Long Island
7h 55m
1 stop
STL11:25 pmLambert-St Louis
Apr 27
STL4:00 pmLambert-St Louis
6h 30m
1 stop
ISP11:30 pmIslip Long Island
$276
Southwest
Mar 30
ISP5:55 pmIslip Long Island
6h 10m
1 stop
STL11:05 pmLambert-St Louis
Apr 6
STL5:20 amLambert-St Louis
5h 20m
1 stop
ISP11:40 amIslip Long Island
$314
Southwest
Apr 23
ISP4:30 pmIslip Long Island
8h 10m
2 stops
STL11:40 pmLambert-St Louis
Apr 27
STL4:00 pmLambert-St Louis
6h 30m
1 stop
ISP11:30 pmIslip Long Island
$319

Frontier flights from Islip, New York to St. Louis

Our best Frontier deals on Islip, New York to St. Louis flight tickets
Frontier
Mar 23
ISP1:22 pmIslip Long Island
7h 03m
1 stop
STL7:25 pmLambert-St Louis
Mar 26
STL8:02 amLambert-St Louis
7h 11m
1 stop
ISP4:13 pmIslip Long Island
$290
Frontier
Mar 16
ISP1:22 pmIslip Long Island
10h 57m
1 stop
STL11:19 pmLambert-St Louis
Mar 19
STL9:05 pmLambert-St Louis
11h 58m
1 stop
ISP10:03 amIslip Long Island
$300
Frontier
Mar 27
ISP1:42 pmIslip Long Island
10h 42m
1 stop
STL11:24 pmLambert-St Louis
Mar 29
STL7:52 amLambert-St Louis
7h 21m
1 stop
ISP4:13 pmIslip Long Island
$545

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 March 11, 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

Thu 4/23

4:30 pm-11:25 pm

1 stop7h 55m

Lambert-St Louis

Mon 4/27

4:00 pm-11:30 pm

1 stop6h 30m

$276

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 3/23

1:22 pm-7:25 pm

1 stop7h 03m

Lambert-St Louis

Thu 3/26

8:02 am-4:13 pm

1 stop7h 11m

$290

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 3/30

5:55 pm-11:05 pm

1 stop6h 10m

Lambert-St Louis

Mon 4/6

5:20 am-11:40 am

1 stop5h 20m

$314

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 4/23

4:30 pm-11:40 pm

2 stops8h 10m

Lambert-St Louis

Mon 4/27

4:00 pm-11:30 pm

1 stop6h 30m

$319
Quickest round-trip

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Tue 9/1

6:05 am-10:05 am

1 stop5h 00m

Lambert-St Louis

Sat 9/5

6:45 am-12:05 pm

1 stop4h 20m

$340

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Tue 9/1

10:55 am-2:50 pm

1 stop4h 55m

Lambert-St Louis

Sat 9/5

5:45 am-2:30 pm

2 stops7h 45m

$345

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Tue 9/1

6:05 am-12:10 pm

2 stops7h 05m

Lambert-St Louis

Sat 9/5

5:45 am-2:30 pm

2 stops7h 45m

$350

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 4/23

8:35 am-3:25 pm

2 stops7h 50m

Lambert-St Louis

Sun 4/26

6:50 pm-11:50 pm

1 stop4h 00m

$362

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 4/23

8:35 am-3:25 pm

2 stops7h 50m

Lambert-St Louis

Mon 4/27

2:10 pm-11:30 pm

2 stops8h 20m

$377

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 3/23

5:15 pm-12:40 am

1 stop8h 25m

Lambert-St Louis

Fri 3/27

4:45 pm-11:55 pm

1 stop6h 10m

$391

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first
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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 $316. 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 $439. 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 morning is the least expensive time of day to depart. momondo users have found prices as low as $349 when looking at flights departing in the morning. At noon is when there is more demand to fly to St. Louis, so prices are often more expensive at around $369 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 10m

Direct flights

None
The fastest flight from Islip, New York to St. Louis takes 6h 10m
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

  • 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 10m.

  • 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
Hermann
Fairview Heights
Florissant
Maryland Heights
O'Fallon
Collinsville
St. Peters
Fenton
Alton
Wentzville
Farmington
Edwardsville
Festus
Clayton
Eureka
Litchfield
Glencoe
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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