They have the pro tournament in mid-April (always the week after the Master's) and April, May and first half of June are generally ideal for golf. March is sometimes OK sometimes not with improvement as the month progresses. We have also found that perhaps the best time to go and play golf is September after Labor Day through October, weather is generally good and prices at many of the courses are less than the are in spring and summer.
The summer is really not as bad as you might imagine. Temps are usually in the mid to high 80s and as an Island there are often breezes that help.