Zanzibar's climate is tropical and generally warm year-round, but rainfall varies significantly by season.
June to October is the driest, most popular season — warm, sunny, and lower humidity, and it also lines up well with Tanzania's own best safari season if you're combining the two.
December to February is also dry and warm, a second good window, though slightly hotter and more humid than June–October.
March to May brings the long rains — heavy, frequent rainfall. Some beach resorts offer meaningfully lower rates during this period if you don't mind the weather risk.
November sees short rains — brief afternoon showers rather than sustained heavy rain, and still a reasonable time to visit.
If you're combining Zanzibar with a mainland safari or a Kilimanjaro climb, June–October and December–February line up well with Tanzania's own best seasons too. Contact us to plan the timing of a combined trip.