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Cheap flights from Islip, New York to St. Louis from $292

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 7/20. 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.
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
$292Frontier
lun, lug 20 - ven, lug 24
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
$329Frontier
lun, ago 3 - mar, ago 4
Southwest Logo
5:50 pm - 12:40 am
ISP
-
STL
7h 50m
2 stops
Southwest Logo
1:40 pm - 9:05 pm
STL
-
ISP
6h 25m
1 stop
$395Southwest
lun, ago 3 - mar, ago 4
Southwest Logo
2:55 pm - 7:15 pm
ISP
-
STL
5h 20m
1 stop
Southwest Logo
9:30 am - 2:50 pm
STL
-
ISP
4h 20m
1 stop
$411Southwest
mar, lug 21 - sab, lug 25
Southwest Logo
12:25 pm - 8:20 pm
ISP
-
STL
8h 55m
2 stops
Southwest Logo
5:10 am - 11:35 am
STL
-
ISP
5h 25m
1 stop
$416Southwest
mar, lug 21 - sab, lug 25
Southwest Logo
5:50 pm - 12:40 am
ISP
-
STL
7h 50m
2 stops
Southwest Logo
10:45 am - 9:05 pm
STL
-
ISP
9h 20m
2 stops
$417Southwest
lun, ago 3 - mar, ago 4
Southwest Logo
4:40 pm - 11:05 pm
ISP
-
STL
7h 25m
2 stops
Southwest Logo
5:00 am - 2:50 pm
STL
-
ISP
8h 50m
2 stops
$444Southwest
mar, lug 21 - sab, lug 25
Southwest Logo
9:10 am - 8:50 pm
ISP
-
STL
12h 40m
2 stops
Southwest Logo
2:50 pm - 11:45 pm
STL
-
ISP
7h 55m
1 stop
$455Southwest
lun, lug 20 - ven, lug 24
Southwest Logo
2:55 pm - 10:30 pm
ISP
-
STL
8h 35m
2 stops
Southwest Logo
4:25 pm - 11:40 pm
STL
-
ISP
6h 15m
2 stops
$484Southwest
mar, lug 21 - ven, lug 24
Southwest Logo
9:10 am - 6:30 pm
ISP
-
STL
10h 20m
2 stops
Southwest Logo
4:35 pm - 11:40 pm
STL
-
ISP
6h 05m
2 stops
$523Southwest
lun, lug 20 - ven, lug 24

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Frontier flights from Islip, New York to St. Louis

Our best Frontier deals on Islip, New York to St. Louis flight tickets
Frontier
Jul 20
ISP10:57 amIslip Long Island
14h 02m
1 stop
STL11:59 pmLambert-St Louis
Jul 24
STL4:09 pmLambert-St Louis
16h 44m
1 stop
ISP9:53 amIslip Long Island
$292
Frontier
Aug 3
ISP10:57 amIslip Long Island
14h 02m
1 stop
STL11:59 pmLambert-St Louis
Aug 4
STL4:09 pmLambert-St Louis
16h 44m
1 stop
ISP9:53 amIslip Long Island
$329

Southwest flights from Islip, New York to St. Louis

Our best Southwest deals on Islip, New York to St. Louis flight tickets
Southwest
Aug 3
ISP5:50 pmIslip Long Island
7h 50m
2 stops
STL12:40 amLambert-St Louis
Aug 4
STL1:40 pmLambert-St Louis
6h 25m
1 stop
ISP9:05 pmIslip Long Island
$395
Southwest
Jul 21
ISP2:55 pmIslip Long Island
5h 20m
1 stop
STL7:15 pmLambert-St Louis
Jul 25
STL9:30 amLambert-St Louis
4h 20m
1 stop
ISP2:50 pmIslip Long Island
$411
Southwest
Jul 21
ISP12:25 pmIslip Long Island
8h 55m
2 stops
STL8:20 pmLambert-St Louis
Jul 25
STL5:10 amLambert-St Louis
5h 25m
1 stop
ISP11:35 amIslip Long Island
$416

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 luglio 8, 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

lun 7/20

10:57 am-11:59 pm

1 stop14h 02m

Lambert-St Louis

ven 7/24

4:09 pm-9:53 am

1 stop16h 44m

$292

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

lun 8/3

10:57 am-11:59 pm

1 stop14h 02m

Lambert-St Louis

mar 8/4

4:09 pm-9:53 am

1 stop16h 44m

$329

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

lun 8/3

5:50 pm-12:40 am

2 stops7h 50m

Lambert-St Louis

mar 8/4

1:40 pm-9:05 pm

1 stop6h 25m

$395
Quickest round-trip

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

mar 7/21

2:55 pm-7:15 pm

1 stop5h 20m

Lambert-St Louis

sab 7/25

9:30 am-2:50 pm

1 stop4h 20m

$411

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

mar 7/21

12:25 pm-8:20 pm

2 stops8h 55m

Lambert-St Louis

sab 7/25

5:10 am-11:35 am

1 stop5h 25m

$416

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

lun 8/3

5:50 pm-12:40 am

2 stops7h 50m

Lambert-St Louis

mar 8/4

10:45 am-9:05 pm

2 stops9h 20m

$417

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

mar 7/21

4:40 pm-11:05 pm

2 stops7h 25m

Lambert-St Louis

sab 7/25

5:00 am-2:50 pm

2 stops8h 50m

$444

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

lun 7/20

9:10 am-8:50 pm

2 stops12h 40m

Lambert-St Louis

ven 7/24

2:50 pm-11:45 pm

1 stop7h 55m

$455

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

mar 7/21

2:55 pm-10:30 pm

2 stops8h 35m

Lambert-St Louis

ven 7/24

4:25 pm-11:40 pm

2 stops6h 15m

$484

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

lun 7/20

9:10 am-6:30 pm

2 stops10h 20m

Lambert-St Louis

ven 7/24

4:35 pm-11:40 pm

2 stops6h 05m

$523

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 $372. 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 $486. 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 $382 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 $414 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

5h 20m

Direct flights

None
The fastest flight from Islip, New York to St. Louis takes 5h 20m
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 5h 20m.

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