Frontier AirlinesDepart18:26
Thu, Dec 10ISP → STL
5h 49m · 1 stop
$234one way, per person
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- Cheapest fare
- $234
- Cheapest month
- December
- Direct flights
- Not recently
- Quickest trip
- 5h 49m
Frontier Airlines · Thu, Dec 10
from $234
Usually 1+ stop
1,480 km
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Cheapest month to fly from Islip to St Louis
Lowest one-way fare per person in each month. Choose a month to see every date.
Cheapest dates in December 2026
The lowest fares we've seen for each day, cheapest first.
Frontier Airlines
jetBlueDepart07:00
Fri, Dec 11ISP → STL
10h 29m · 3 stops
$298one way, per person
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Plan the rest of your trip to St Louis
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About flights from Islip to St Louis
Islip (ISP) and St Louis (STL) are about 1,480 km apart. We haven't seen direct fares on this route recently, so expect at least one stop; the quickest journey we've seen takes about 5h 49m. Over the next few months, one-way fares start from $234, and December 2026 is currently the cheapest month to fly.
These prices come from searches travellers made in the last 48 hours, so they move quickly. If you see a good fare, it's worth booking soon. FlightsExp is free to use: you book directly with our travel partner.
Frequently asked questions
How much is a flight from Islip to St Louis?
The cheapest one-way fare we've seen recently is $234 with Frontier Airlines, departing Thursday, December 10, 2026.
What is the cheapest month to fly from Islip to St Louis?
December 2026 currently has the lowest fares, from $234 one way.
Are there direct flights from Islip to St Louis?
We haven't seen direct fares recently, so most journeys include at least one stop.
How long is the flight from Islip to St Louis?
The quickest journey we've seen takes about 5h 49m. Islip and St Louis are around 1,480 km apart.
Which airlines fly from Islip to St Louis?
Recent fares on this route were with Frontier Airlines and jetBlue.
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