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Cheap flights from Islip, New York to St. Louis from $135

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 1/9. 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.
Frontier Logo
8:40 pm - 7:50 amISP-STL
12h 10m1 stop
Frontier Logo
8:50 am - 7:51 pmSTL-ISP
10h 01m1 stop
$162Frontier
Find Deal
Thu, Jan 8 - Mon, Jan 12
Frontier Logo
12:20 pm - 10:33 pmISP-STL
11h 13m1 stop
Frontier Logo
10:40 am - 7:40 pmSTL-ISP
8h 00m1 stop
$234Frontier
Find Deal
Thu, Dec 18 - Mon, Dec 22
Frontier Logo
2:04 pm - 10:33 pmISP-STL
9h 29m1 stop
Frontier Logo
10:40 am - 7:40 pmSTL-ISP
8h 00m1 stop
$283Frontier
Find Deal
Sun, Dec 21 - Mon, Dec 22
Frontier Logo
1:27 pm - 7:42 pmISP-STL
7h 15m1 stop
Frontier Logo
10:40 am - 7:40 pmSTL-ISP
8h 00m1 stop
$298Frontier
Find Deal
Fri, Dec 19 - Mon, Dec 22
Frontier Logo
2:04 pm - 10:33 pmISP-STL
9h 29m1 stop
Frontier Logo
10:40 am - 7:40 pmSTL-ISP
8h 00m1 stop
$559Frontier
Find Deal
Sun, Dec 21 - Fri, Dec 26
Frontier Logo
1:27 pm - 7:42 pmISP-STL
7h 15m1 stop
Frontier Logo
10:40 am - 7:40 pmSTL-ISP
8h 00m1 stop
$574Frontier
Find Deal
Fri, Dec 19 - Fri, Dec 26
Frontier Logo
2:04 pm - 10:33 pmISP-STL
9h 29m1 stop
Frontier Logo
10:40 am - 7:40 pmSTL-ISP
8h 00m1 stop
$609Frontier
Find Deal
Mon, Dec 22 - Fri, Dec 26
Frontier Logo
8:19 pm - 7:13 amISP-STL
11h 54m1 stop
Frontier Logo
6:00 am - 7:11 pmSTL-ISP
12h 11m1 stop
$701Frontier
Find Deal
Fri, Mar 6 - Sun, Mar 8
Frontier Logo
12:20 pm - 10:33 pmISP-STL
11h 13m1 stop
Frontier Logo
10:40 am - 7:40 pmSTL-ISP
8h 00m1 stop
$719Frontier
Find Deal
Thu, Dec 25 - Fri, Dec 26
Frontier Logo
12:20 pm - 10:33 pmISP-STL
11h 13m1 stop
Frontier Logo
10:40 am - 7:40 pmSTL-ISP
8h 00m1 stop
$763Frontier
Find Deal
Tue, Dec 23 - Fri, Dec 26

Frontier flights from Islip, New York to St. Louis

Our best Frontier deals on Islip, New York to St. Louis flight tickets
Frontier
Jan 8
ISP8:40 pmIslip Long Island
12h 10m
1 stop
STL7:50 amLambert-St Louis
Jan 12
STL8:50 amLambert-St Louis
10h 01m
1 stop
ISP7:51 pmIslip Long Island
$162
Find similar
Frontier
Dec 21
ISP2:04 pmIslip Long Island
9h 29m
1 stop
STL10:33 pmLambert-St Louis
Dec 22
STL10:40 amLambert-St Louis
8h 00m
1 stop
ISP7:40 pmIslip Long Island
$283
Find similar
Frontier
Dec 19
ISP1:27 pmIslip Long Island
7h 15m
1 stop
STL7:42 pmLambert-St Louis
Dec 22
STL10:40 amLambert-St Louis
8h 00m
1 stop
ISP7:40 pmIslip Long Island
$298
Find similar

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 December 3, 2025.
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

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 1/8

8:40 pm-7:50 am

1 stop12h 10m

Lambert-St Louis

Mon 1/12

8:50 am-7:51 pm

1 stop10h 01m

$162

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 12/18

12:20 pm-10:33 pm

1 stop11h 13m

Lambert-St Louis

Mon 12/22

10:40 am-7:40 pm

1 stop8h 00m

$234

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Sun 12/21

2:04 pm-10:33 pm

1 stop9h 29m

Lambert-St Louis

Mon 12/22

10:40 am-7:40 pm

1 stop8h 00m

$283

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 12/19

1:27 pm-7:42 pm

1 stop7h 15m

Lambert-St Louis

Mon 12/22

10:40 am-7:40 pm

1 stop8h 00m

$298

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Sun 12/21

2:04 pm-10:33 pm

1 stop9h 29m

Lambert-St Louis

Fri 12/26

10:40 am-7:40 pm

1 stop8h 00m

$559

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 12/19

1:27 pm-7:42 pm

1 stop7h 15m

Lambert-St Louis

Fri 12/26

10:40 am-7:40 pm

1 stop8h 00m

$574

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 12/22

2:04 pm-10:33 pm

1 stop9h 29m

Lambert-St Louis

Fri 12/26

10:40 am-7:40 pm

1 stop8h 00m

$609

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 3/6

8:19 pm-7:13 am

1 stop11h 54m

Lambert-St Louis

Sun 3/8

6:00 am-7:11 pm

1 stop12h 11m

$701

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 12/25

12:20 pm-10:33 pm

1 stop11h 13m

Lambert-St Louis

Fri 12/26

10:40 am-7:40 pm

1 stop8h 00m

$719

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Tue 12/23

12:20 pm-10:33 pm

1 stop11h 13m

Lambert-St Louis

Fri 12/26

10:40 am-7:40 pm

1 stop8h 00m

$763

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 14 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 $312. 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 $442. 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 $343 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 $370 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

12h 10m

Direct flights

None
The fastest flight from Islip, New York to St. Louis takes 12h 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 7h 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 many operators does momondo search for flights from Islip Long Island Airport to Lambert-St Louis Airport?

  • 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.

  • What is the most popular airline from Islip, New York to St. Louis?

Best airlines flying from Islip, New York to St. Louis

Compare and see reviews for airlines that fly from Islip, New York to St. Louis with momondo
Airline
Rating
Free Cancellation
Price
SouthwestPriceFrom $259Free CancellationRating
8.0
4,253 reviews
Search Southwest flights

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
Fenton
Wentzville
Collinsville
St. Peters
Alton
Farmington
Clayton
Festus
Glencoe
Edwardsville
Eureka
Litchfield
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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