Latest deals
Insights
When to book
FAQs
Price Alerts

Cheap flights from Islip, New York to St. Louis from $186

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 6/5. 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
0 bags

Save money when you book flights with momondo

Big names and deals

Big names and deals

Search 100s of travel sites to compare prices.

Filter for what you want

Filter for what you want

Free Wi-Fi? Stopover? Instantly customize your results.

Trusted and free

Trusted and free

We’re completely free to use - no hidden charges or fees.

Price Alerts

Price Alerts

Not ready to book? to track prices.
Search flight deals

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
6:50 pm - 11:50 pm
STL
-
ISP
4h 00m
1 stop
$313Southwest
Fri, May 8 - Sun, May 10
Southwest Logo
4:30 pm - 11:40 pm
ISP
-
STL
8h 10m
2 stops
Southwest Logo
6:50 pm - 11:50 pm
STL
-
ISP
4h 00m
1 stop
$318Southwest
Fri, May 8 - Sun, May 10
Southwest Logo
12:25 pm - 8:25 pm
ISP
-
STL
9h 00m
2 stops
Southwest Logo
5:05 am - 2:05 pm
STL
-
ISP
8h 00m
1 stop
$323Southwest
Wed, Jun 24 - Sat, Jun 27
Multiple Airlines Logo
11:12 am - 12:21 am
ISP
-
STL
14h 09m
1 stop
Multiple Airlines Logo
4:19 pm - 11:16 am
STL
-
ISP
41h 57m
2 stops
$337Multiple Airlines
Thu, May 14 - Sun, May 17
Frontier Logo
11:12 am - 12:21 am
ISP
-
STL
14h 09m
1 stop
Frontier Logo
4:19 pm - 10:05 am
STL
-
ISP
16h 46m
1 stop
$341Frontier
Thu, May 14 - Sun, May 17
Southwest Logo
9:00 am - 3:15 pm
ISP
-
STL
7h 15m
1 stop
Southwest Logo
2:25 pm - 11:30 pm
STL
-
ISP
8h 05m
2 stops
$353Southwest
Wed, May 20 - Fri, May 22
Southwest Logo
12:25 pm - 8:25 pm
ISP
-
STL
9h 00m
2 stops
Southwest Logo
3:45 pm - 11:10 pm
STL
-
ISP
6h 25m
2 stops
$358Southwest
Wed, Jun 24 - Sat, Jun 27
Southwest Logo
9:00 am - 3:15 pm
ISP
-
STL
7h 15m
1 stop
Southwest Logo
5:00 am - 11:50 am
STL
-
ISP
5h 50m
1 stop
$384Southwest
Wed, May 20 - Fri, May 22
Southwest Logo
6:55 am - 1:25 pm
ISP
-
STL
7h 30m
2 stops
Southwest Logo
2:25 pm - 11:30 pm
STL
-
ISP
8h 05m
2 stops
$385Southwest
Wed, May 20 - Fri, May 22
Southwest Logo
2:55 pm - 7:15 pm
ISP
-
STL
5h 20m
1 stop
Southwest Logo
5:05 am - 2:05 pm
STL
-
ISP
8h 00m
1 stop
$387Southwest
Wed, Jun 24 - Sat, Jun 27

Southwest flights from Islip, New York to St. Louis

Our best Southwest deals on Islip, New York to St. Louis flight tickets
Southwest
May 8
ISP5:10 pmIslip Long Island
7h 30m
1 stop
STL11:40 pmLambert-St Louis
May 10
STL6:50 pmLambert-St Louis
4h 00m
1 stop
ISP11:50 pmIslip Long Island
$313
Southwest
May 8
ISP4:30 pmIslip Long Island
8h 10m
2 stops
STL11:40 pmLambert-St Louis
May 10
STL6:50 pmLambert-St Louis
4h 00m
1 stop
ISP11:50 pmIslip Long Island
$318
Southwest
Jun 24
ISP12:25 pmIslip Long Island
9h 00m
2 stops
STL8:25 pmLambert-St Louis
Jun 27
STL5:05 amLambert-St Louis
8h 00m
1 stop
ISP2:05 pmIslip Long Island
$323

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 12, 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
Quickest round-trip

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 5/8

5:10 pm-11:40 pm

1 stop7h 30m

Lambert-St Louis

Sun 5/10

6:50 pm-11:50 pm

1 stop4h 00m

$313

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 5/8

4:30 pm-11:40 pm

2 stops8h 10m

Lambert-St Louis

Sun 5/10

6:50 pm-11:50 pm

1 stop4h 00m

$318

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 6/24

12:25 pm-8:25 pm

2 stops9h 00m

Lambert-St Louis

Sat 6/27

5:05 am-2:05 pm

1 stop8h 00m

$323

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 5/14

11:12 am-12:21 am

1 stop14h 09m

Lambert-St Louis

Sun 5/17

4:19 pm-11:16 am

2 stops41h 57m

$337

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 5/14

11:12 am-12:21 am

1 stop14h 09m

Lambert-St Louis

Sun 5/17

4:19 pm-10:05 am

1 stop16h 46m

$341

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 5/20

9:00 am-3:15 pm

1 stop7h 15m

Lambert-St Louis

Fri 5/22

2:25 pm-11:30 pm

2 stops8h 05m

$353

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 6/24

12:25 pm-8:25 pm

2 stops9h 00m

Lambert-St Louis

Sat 6/27

3:45 pm-11:10 pm

2 stops6h 25m

$358

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 5/20

9:00 am-3:15 pm

1 stop7h 15m

Lambert-St Louis

Fri 5/22

5:00 am-11:50 am

1 stop5h 50m

$384

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 5/20

6:55 am-1:25 pm

2 stops7h 30m

Lambert-St Louis

Fri 5/22

2:25 pm-11:30 pm

2 stops8h 05m

$385

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 6/24

2:55 pm-7:15 pm

1 stop5h 20m

Lambert-St Louis

Sat 6/27

5:05 am-2:05 pm

1 stop8h 00m

$387

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 16 resultsSorted by cheapest first
1
2

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 $330. 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 $453. 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 $366 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 $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

5h 25m

Direct flights

None
The fastest flight from Islip, New York to St. Louis takes 5h 25m
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 25m.

  • 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
Clayton
Festus
Eureka
Edwardsville
Litchfield
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.

An easier way to manage your St. Louis trip

We make it super easy to schedule, organize and travel with friends or family. Trips is free — and available to use no matter where you book.
Start using Trips
Find my bookings

Get notified when prices go down

Daily price changes in your inbox - only with Price Alerts.
1 adult
Tue 5/12
Tue 5/19
By creating a price alert you accept our terms of use and privacy policy.

Find better results for your trip to the United States