There's nothing like an all-inclusive holiday in Gros Islet to refresh you, especially when you know what to expect from the elements. Here's some information to help you choose when to book: The hottest months are usually September and August, with an average temperature of 28°C, while the coldest months are February and March, with an average of 26°C. February and March are the driest months, while October and August are the rainiest months.