I would say spring by your choices, but some heavier clothes may be needed. We have been in late Nov. and it can be very cool at night, It is to cool to do much on the deck at night and even the days might not be that warm. The last couple of years have been cool for long periods but no extreme cold.
Tom
Depends where you're from. If you're from a warm climate to start with (i.e. Florida, south Texas, etc.) you may feel cooler than those of us "Eskimos" from up north! Still, I think 60's and 70's seem to be the norm, with occasional warmer days than that. I have been in Nassau in Feb. and experienced humid low 80's.
Aim
Trust me 50s at night out on the water is cold no mater where you come from. I happen to come from S.Fla. but it doesn't matter it's cold at 50-60 degrees and the wind blowing.Its better to take some warm cloths than be sorry. I know there isn't much Karen doesn't know and she is a travel agent but I have been on 23 and have seen some very disgruntled passengers any where from Nov. through early April the weather the last few years has been very windy causing rough seas and cool temperatures.
Thomas