Kaskazi and kusi are the two monsoon wind patterns that shape Zanzibar’s climate and, more practically, affect swimming conditions, sea temperature and even which side of the island feels most pleasant at different times of year.

Kaskazi is the northeast monsoon, roughly running from December through March. It brings warmer, calmer seas and generally lighter winds, and this period, alongside being one of the driest stretches, is considered peak season for beach relaxation and swimming. It overlaps with excellent safari timing on the mainland too, including the Ndutu calving season, which makes it a strong window for a combined trip.

Kusi is the southeast monsoon, roughly June through September. It brings stronger, cooler winds and rougher seas, particularly noticeable on the east coast. This is not necessarily a bad time to visit, temperatures are still warm and it is a genuinely good period for kitesurfing given the reliable wind, particularly around Paje, which has become a kitesurfing hub partly because of these exact conditions. Swimming is still perfectly possible, but the sea has more chop than during kaskazi.

The long rains fall roughly April into May, and this is the quietest and cheapest time to visit, with some smaller properties closing entirely. The short rains fall around November, generally lighter and more intermittent, and often still a workable time to travel.

For a straightforward beach holiday with the calmest seas, aim for kaskazi months. If you want wind for kitesurfing or do not mind a livelier sea, kusi works well and comes with fewer crowds and often better rates.