June to October or December to February are the best times to visit Zanzibar, offering perfect mix of sunny, hot, cool and dry weather with very little or no rain during December – February making it perfect for sightseeing and indulging in outdoor activities
Visiting Zanzibar in December the weather is extremely nice and visitors can expect to feel daytime high temperatures in the range of 28°C (82°F) and at night 25°C (77°F). The average water temperature at the beaches around the island is 27°C (81°C).Visitors in December will experience joyous festive and celebrations. December 9th Zanzibar’s Independence and Republic Day, December 25th and 26th Christmas, December 31st new years eve
Visiting Zanzibar in January visitors can expect a daytime high temperature of around 29°C (84°F). It is very sunny and warm in January and visitors are advised to pack light, cool clothing. Nightly low temperatures in the range of about 25°C (77°F) can be expected this month. The average temperature of the sea around Zanzibar in January is 29°C (84°F).
Visiting Zanzibar in February
during the day average temperature 29°C (84°F) time and 26°C (79°F) at night. Visitors will find the weather perfect retreat for swimming, snorkeling, diving, and many other activities. World music lovers will be enthralled with the Sauti za Busara Music Festival, which happens around the second week of February and runs for 5 straight days.
Visiting Zanzibar in March
it is extremely sunny and breezy with slight rain 5-6 days within March. The average temperature during the day 28°C (82°F) and lows at night to 24°C (75°F) which is the perfect weather for taking in the nightlife and strolling. Humidity is surprisingly low at 66%
Visiting Zanzibar in April
raining season visitors are likely to stay inside for most of the days in April however you can visit historical/nature sites,engage in culture activitie. Although April is extremely we the average day temperature 27°C (81°F) and night 24°C (75°F)
Visiting Zanzibar in May
expect short rainfall or light showers with little or no sunshine average day temperature 27°C (81°F) and 24°C (75°F) at night
Visiting Zanzibar in June
beginning of long dry season, it is often sunny very little showers. Average temperature 26°C (79°Fday time and night 23°C (73°F)
Visiting Zanzibar in July – August
perfect weather dry season with average temperature of 26°C (79°F), clear skies, cool winds and waters perfect for sightseeing and indulging in outdoor activities
Visiting Zanzibar in September – October – November mix up weather, sometimes we will surprise you with short rain especially in November, but day heat will give you blue sky back very quickly 
The ocean is warm and temperature hot but comfortable to do excursions as little fresh wind will balance it for you!