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Cheap flights from Islip, New York to St. Louis from $161

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 12/22. 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
10:19 am - 10:33 pmISP-STL
13h 14m1 stop
Frontier Logo
3:30 pm - 10:44 pmSTL-ISP
6h 14m1 stop
$213Frontier
Find Deal
Sat, Dec 6 - Wed, Dec 10
Frontier Logo
1:10 pm - 7:11 pmISP-STL
7h 01m1 stop
Frontier Logo
8:45 am - 4:06 pmSTL-ISP
6h 21m1 stop
$252Frontier
Find Deal
Fri, Feb 27 - Sun, Mar 1
Multiple Airlines Logo
4:05 pm - 1:52 pmISP-STL
22h 47m2 stops
Multiple Airlines Logo
3:30 pm - 9:13 amSTL-ISP
16h 43m1 stop
$254Multiple Airlines
Find Deal
Sat, Dec 6 - Wed, Dec 10
Southwest Logo
5:15 pm - 12:40 amISP-STL
8h 25m1 stop
Southwest Logo
4:55 pm - 11:50 pmSTL-ISP
5h 55m1 stop
$340Southwest
Find Deal
Fri, Mar 6 - Sun, Mar 8
Southwest Logo
2:00 pm - 8:55 pmISP-STL
7h 55m2 stops
Southwest Logo
4:55 pm - 11:50 pmSTL-ISP
5h 55m1 stop
$345Southwest
Find Deal
Fri, Mar 6 - Sun, Mar 8
Southwest Logo
2:00 pm - 8:55 pmISP-STL
7h 55m2 stops
Southwest Logo
12:45 pm - 10:55 pmSTL-ISP
9h 10m2 stops
$380Southwest
Find Deal
Fri, Mar 6 - Sun, Mar 8
Frontier Logo
8:19 pm - 7:13 amISP-STL
11h 54m1 stop
Frontier Logo
6:00 am - 7:11 pmSTL-ISP
12h 11m1 stop
$721Frontier
Find Deal
Fri, Mar 6 - Sun, Mar 8

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 6
ISP10:19 amIslip Long Island
13h 14m
1 stop
STL10:33 pmLambert-St Louis
Dec 10
STL3:30 pmLambert-St Louis
6h 14m
1 stop
ISP10:44 pmIslip Long Island
$213
Find similar
Frontier
Feb 27
ISP1:10 pmIslip Long Island
7h 01m
1 stop
STL7:11 pmLambert-St Louis
Mar 1
STL8:45 amLambert-St Louis
6h 21m
1 stop
ISP4:06 pmIslip Long Island
$252
Find similar

Southwest flights from Islip, New York to St. Louis

Our best Southwest deals on Islip, New York to St. Louis flight tickets
Southwest
Mar 6
ISP5:15 pmIslip Long Island
8h 25m
1 stop
STL12:40 amLambert-St Louis
Mar 8
STL4:55 pmLambert-St Louis
5h 55m
1 stop
ISP11:50 pmIslip Long Island
$340
Find similar
Southwest
Mar 6
ISP2:00 pmIslip Long Island
7h 55m
2 stops
STL8:55 pmLambert-St Louis
Mar 8
STL4:55 pmLambert-St Louis
5h 55m
1 stop
ISP11:50 pmIslip Long Island
$345
Find similar
Southwest
Mar 6
ISP2:00 pmIslip Long Island
7h 55m
2 stops
STL8:55 pmLambert-St Louis
Mar 8
STL12:45 pmLambert-St Louis
9h 10m
2 stops
ISP10:55 pmIslip Long Island
$380
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 November 22, 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

Sat 12/6

10:19 am-10:33 pm

1 stop13h 14m

Lambert-St Louis

Wed 12/10

3:30 pm-10:44 pm

1 stop6h 14m

$213

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 2/27

1:10 pm-7:11 pm

1 stop7h 01m

Lambert-St Louis

Sun 3/1

8:45 am-4:06 pm

1 stop6h 21m

$252

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Sat 12/6

4:05 pm-1:52 pm

2 stops22h 47m

Lambert-St Louis

Wed 12/10

3:30 pm-9:13 am

1 stop16h 43m

$254

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 3/6

5:15 pm-12:40 am

1 stop8h 25m

Lambert-St Louis

Sun 3/8

4:55 pm-11:50 pm

1 stop5h 55m

$340

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 3/6

2:00 pm-8:55 pm

2 stops7h 55m

Lambert-St Louis

Sun 3/8

4:55 pm-11:50 pm

1 stop5h 55m

$345

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 3/6

2:00 pm-8:55 pm

2 stops7h 55m

Lambert-St Louis

Sun 3/8

12:45 pm-10:55 pm

2 stops9h 10m

$380

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

$721

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 12/22

2:04 pm-10:33 pm

1 stop9h 29m

$161

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 12/22

2:04 pm-10:33 pm

1 stop9h 29m

$226

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 11 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 $319. 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 $344 when looking at flights departing in the morning. In the evening is when there is more demand to fly to St. Louis, so prices are often more expensive at around $377 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

Direct flights

None
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.
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  • 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 01m.

  • 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
4,252 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
Florissant
Maryland Heights
O'Fallon
Wentzville
Fenton
Collinsville
St. Peters
Alton
Farmington
Festus
Glencoe
Edwardsville
Clayton
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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Mon 12/22
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