Yep, that's when we go each year, it's risky being in hurricane season and I hate to put a label on it but mostly just afternoon showers, anywhere from 10 min to 2 hours long... Good nap, relaxation, bar, "alone time" opportunity!!!
Average High / Low of 87/77 through most of Sept. A little "wetter" than other months, but not by much...As long as there is no major swirling storm in the vicinity you'll be just dandy. We've visited in August, November, and March and a few others I can't remember. Only one trip did we see a significant amount of rain. That's why it's paradise. It's pretty dang nice all the time!