August can be a great month to travel to the Caribbean if you know what to expect! It will be hotter, more humid, and likely have rain showers in the afternoon (which will clear up quickly) than you would expect to find in high season from December through March. If you're willing to plan around this a little, you can have a wonderful trip. If you love the water this would be the perfect time of year to go - it's probably a bit hot and humid to do a lot of sight-seeing though. I always plan for an afternoon siesta to avoid the rain showers if I go at this time of year.