Is 1 hour and 20 minutes enough time to connect from Jet Blue Flight # 3 from JFK to San Juan and then Jet Blue flight# 850 to St. Martin? Thank you

Yes, that is plenty of time. JetBlue uses terminal A in San Juan and there are only 7 gates.

On the way down you should be fine with that connection. On your return allow at least 90 minutes between flights as you have to clear Immigration, Customs and TSA.

Of course that advice assume your inbound flight is "on time" or relatively close to it.

We always stay over night in PR on the way back. Flights seem to leave late from St. Martin an customs is always a unknown. Much more relaxed knowing we don't have to run or get stuck.

Going down that is plenty of time, if your inbound flight is on time. Jet Blue's gates are all together, so no appreciable walking time in between. I guess that maybe JB has increased their connection times between flights in SJU. They had been regularly scheduling flights with connection times (not necessarily from JFK) with as little as TWENTY MINUTES connection time in SJU on the way down, especially from Florida. Just nuts..

In July on the way back, we made it to the plane as the last person was boarding.