Weather in British Indian Ocean Territory

The British Indian Ocean Territory is not open to tourism and there is no meaningful best time to visit in any practical travel planning sense. For the rare liveaboard dive vessels that have historically obtained special permits to access Chagos outer island reefs — a practice that has become increasingly restricted — the calmer sea conditions of April to November, during the northeast monsoon transition and through the southern winter, offered the most comfortable sailing and diving conditions.

The Indian Ocean around Chagos experiences two main monsoon seasons: the northwest monsoon from November to March, which can bring rougher seas, and the southeast monsoon from May to October. The transition months of April and October historically offered the best sailing windows. Water temperatures remain a consistent 27–29°C year-round. The remarkable clarity of the water, with visibility often exceeding 30 metres, is a constant in these pristine, undisturbed seas.