If you can afford a little bit of $$ and have an SSB...Chris Parker gives superb weather and routing advice as he is both an accomplished cruiser AND a great weather man! You can find out about his services at
www.caribwx.com and clicking the "offerings" link.
If you can't afford the service...you can still listen in on the SSB and hope that the general forcasts cover precisely where you are. We used both his E-mail and SSB service for over a year and always felt it was money well spent as he was so much more precise than NOAA.
Here's more weather stuff for the Caribbean available on SSB:
Link to Carribbean Compass