Shird, fret not :) And do not waste the fun of your excitement and anticipation time, looking at weather forecasts !
We saw the same thing before we traveled last August (yes, I looked, lol) and we needn't not have been worried at all!! It rained one night for about an hour or so, and I think one little, little shower one day and the sun popped right back out - other than that, it was beautiful, hot and humid every day. With a tropical climate, there's always the chance of rain on those silly weather sites, and it's pretty hard to predict the weather down there for two weeks. You will be in a beautiful place and even with a little rain, it's vacation and you're not at home!
Enjoy your trip :D