Mafia’s tropical climate is defined by two distinct rainy seasons. The short rains last from November to December, while the long rains last from March to May. If diving is your top priority, try to avoid traveling during the rainy seasons when underwater visibility is reduced. Some lodges close for the duration of the long rains. For sunny, dry weather, plan to visit from August to October (slightly cooler) or from late December to mid-March (hotter and more humid). June and July are generally cool and dry but can be windy, affecting sea conditions. September to March is whale shark season.
If you’re going for diving, then pick your month carefully. Chole Bay can be dived year-round, but the deeper channels are only viable from August to November. October to February has the best visibility, although it’s rarely below 15m at any time of year. For the best beach conditions aim for late May to the start of the short rainy season in November. September to early March is prime whale shark season so it’s really only mid-March to mid-May that should be avoided completely, when the island receives most of its rain