My first cruise leaves on Sunday, on the Legend. We had to book so late in the year due to my job (I really cannot take vacations until September, and then I only have a small window where my business is "slow" enough that I can be away for a week.) I purposefully chose the late October/early November time frame to avoid the majority of hurricane season; but I also found a couple of websites that are quite handy when looking at the turbulence factor, etc.
I've linked to them below and hope it helps.
Turbulence Forecast - Cruise Forecast - Wave Heights
Intellicast - Caribbean Satellite in United States