When the wind direction changes, they reverse the runway, which for some reason becomes shorter. That is what happened when they unloaded passengers and bags and burnt fuel. That can, and does, happen any time of year.

I'm guessing this is purely about demand. It certainly benefits people coming from airports with direct service to Miami but not San Juan. It also benefits people whose final destination is not Tortola, as it gives them more time to get where they're going.

George may know, but I'm wondering if it would be possible to have a flight come in later in the evening and leave early in the morning. That would benefit travelers from further away, who can't get to Miami before 10 am.