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Cheap flights from Islip, New York to St. Louis from $95

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 7/7. 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
5:10 pm - 11:40 pm
ISP
-
STL
7h 30m
1 stop
Southwest Logo
3:55 pm - 10:40 pm
STL
-
ISP
5h 45m
1 stop
$228Southwest
Thu, May 28 - Tue, Jun 2
Frontier Logo
11:00 am - 8:55 am
ISP
-
STL
22h 55m
2 stops
Frontier Logo
4:19 pm - 10:05 am
STL
-
ISP
16h 46m
1 stop
$230Frontier
Thu, May 28 - Tue, Jun 2
Southwest Logo
4:30 pm - 11:15 pm
ISP
-
STL
7h 45m
2 stops
Southwest Logo
6:35 am - 1:50 pm
STL
-
ISP
6h 15m
1 stop
$279Southwest
Mon, May 11 - Wed, May 13
Frontier Logo
11:00 am - 8:11 pm
ISP
-
STL
34h 11m
2 stops
Frontier Logo
3:33 pm - 10:05 am
STL
-
ISP
17h 32m
2 stops
$288Frontier
Thu, May 28 - Tue, Jun 2
Southwest Logo
4:30 pm - 11:15 pm
ISP
-
STL
7h 45m
2 stops
Southwest Logo
5:35 am - 1:50 pm
STL
-
ISP
7h 15m
2 stops
$300Southwest
Mon, May 11 - Wed, May 13
Southwest Logo
6:05 pm - 12:05 am
ISP
-
STL
7h 00m
1 stop
Southwest Logo
6:40 am - 11:45 am
STL
-
ISP
4h 05m
1 stop
$313Southwest
Fri, Jun 12 - Sun, Jun 14
Southwest Logo
4:10 pm - 9:05 pm
ISP
-
STL
5h 55m
1 stop
Southwest Logo
1:15 pm - 6:30 pm
STL
-
ISP
4h 15m
1 stop
$318Southwest
Wed, May 6 - Tue, May 12
Southwest Logo
12:30 pm - 8:00 pm
ISP
-
STL
8h 30m
2 stops
Southwest Logo
6:35 am - 1:50 pm
STL
-
ISP
6h 15m
1 stop
$324Southwest
Wed, May 6 - Tue, May 12
Southwest Logo
5:50 pm - 12:05 am
ISP
-
STL
7h 15m
2 stops
Southwest Logo
6:40 am - 11:45 am
STL
-
ISP
4h 05m
1 stop
$333Southwest
Fri, Jun 12 - Sun, Jun 14
Southwest Logo
6:30 am - 12:50 pm
ISP
-
STL
7h 20m
2 stops
Southwest Logo
2:10 pm - 10:40 pm
STL
-
ISP
7h 30m
2 stops
$345Southwest
Wed, May 6 - Tue, May 12

Southwest flights from Islip, New York to St. Louis

Our best Southwest deals on Islip, New York to St. Louis flight tickets
Southwest
May 28
ISP5:10 pmIslip Long Island
7h 30m
1 stop
STL11:40 pmLambert-St Louis
Jun 2
STL3:55 pmLambert-St Louis
5h 45m
1 stop
ISP10:40 pmIslip Long Island
$228
Southwest
May 11
ISP4:30 pmIslip Long Island
7h 45m
2 stops
STL11:15 pmLambert-St Louis
May 13
STL6:35 amLambert-St Louis
6h 15m
1 stop
ISP1:50 pmIslip Long Island
$279
Southwest
May 11
ISP4:30 pmIslip Long Island
7h 45m
2 stops
STL11:15 pmLambert-St Louis
May 13
STL5:35 amLambert-St Louis
7h 15m
2 stops
ISP1:50 pmIslip Long Island
$300

Frontier flights from Islip, New York to St. Louis

Our best Frontier deals on Islip, New York to St. Louis flight tickets
Frontier
May 28
ISP11:00 amIslip Long Island
22h 55m
2 stops
STL8:55 amLambert-St Louis
Jun 2
STL4:19 pmLambert-St Louis
16h 46m
1 stop
ISP10:05 amIslip Long Island
$230
Frontier
May 28
ISP11:00 amIslip Long Island
34h 11m
2 stops
STL8:11 pmLambert-St Louis
Jun 2
STL3:33 pmLambert-St Louis
17h 32m
2 stops
ISP10:05 amIslip Long Island
$288
Frontier
May 4
ISP4:07 pmIslip Long Island
8h 12m
1 stop
STL11:19 pmLambert-St Louis
May 8
STL4:19 pmLambert-St Louis
16h 46m
1 stop
ISP10:05 amIslip Long Island
$401

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 April 23, 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 5/28

5:10 pm-11:40 pm

1 stop7h 30m

Lambert-St Louis

Tue 6/2

3:55 pm-10:40 pm

1 stop5h 45m

$228

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 5/28

11:00 am-8:55 am

2 stops22h 55m

Lambert-St Louis

Tue 6/2

4:19 pm-10:05 am

1 stop16h 46m

$230

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 5/11

4:30 pm-11:15 pm

2 stops7h 45m

Lambert-St Louis

Wed 5/13

6:35 am-1:50 pm

1 stop6h 15m

$279

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 5/28

11:00 am-8:11 pm

2 stops34h 11m

Lambert-St Louis

Tue 6/2

3:33 pm-10:05 am

2 stops17h 32m

$288

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 5/11

4:30 pm-11:15 pm

2 stops7h 45m

Lambert-St Louis

Wed 5/13

5:35 am-1:50 pm

2 stops7h 15m

$300

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 6/12

6:05 pm-12:05 am

1 stop7h 00m

Lambert-St Louis

Sun 6/14

6:40 am-11:45 am

1 stop4h 05m

$313
Quickest round-trip

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 5/6

4:10 pm-9:05 pm

1 stop5h 55m

Lambert-St Louis

Tue 5/12

1:15 pm-6:30 pm

1 stop4h 15m

$318

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 5/6

12:30 pm-8:00 pm

2 stops8h 30m

Lambert-St Louis

Tue 5/12

6:35 am-1:50 pm

1 stop6h 15m

$324

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 6/12

5:50 pm-12:05 am

2 stops7h 15m

Lambert-St Louis

Sun 6/14

6:40 am-11:45 am

1 stop4h 05m

$333

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 5/6

6:30 am-12:50 pm

2 stops7h 20m

Lambert-St Louis

Tue 5/12

2:10 pm-10:40 pm

2 stops7h 30m

$345

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 $334. 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 $455. 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 $370 when looking at flights departing in the morning. In the afternoon is when there is more demand to fly to St. Louis, so prices are often more expensive at around $378 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

7h 00m

Direct flights

None
The fastest flight from Islip, New York to St. Louis takes 7h 00m
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 7h 00m.

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

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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