Zanzibar islands are located off the east coast of Tanzania and have a beautiful climate. Although the islands are located in the equatorial region at 6 degrees south, but the rain is neither that heavy as on the other equatorial islands nor the weather too humid; thanks to the strong cool breezes associated with the Northeast and the Southwest Monsoons. Following is a brief description of the temperature and the rainfall regime.
There are no extremes of temperatures. Mean maximum of the hottest month, March, is 93 F and the mean maximum of the coolest month, August is 83 F so the annual mean maximum range is only 10 degrees. The corresponding nighttime lows for hottest and coolest months are 77 and 72 F respectively- a difference of only 5 degrees F.
May to September are relatively cooler months while November to March are relatively hotter months.
The islands are visited by two monsoons i.e., the Northeast Monsoon and Southwest Monsoon so no month of the year is dry. The south west rain maxima occurs in the Month of April which records 13 inches of rainfall. The maximum rainfall recorded in the south east monsoon season is in November which is 7 inches. The lowest rain is recorded in the month of August which is 2 inches.
The total annual rainfall is 60 inches which is quite moderate for the equatorial region since nowhere on the equatorial islands, it is less than 80 inches. Some islands of Malaysia and Indonesia even record up to 200 inches of rainfall annually.
It is this peculiarity of Zanzibar islands that adds a constant beauty to the climate of the islands and the tourist can visit free of mind without any danger of exceptionally heavy rain all the year round.
Relative Humidity & Wind Speed
The relative humidity, owing to their island nature and due to the visit of the two monsoons discussed above remains high throughout the year and seldom falls below 60 percent in the afternoons but the local sea breeze and the cools winds brought by the monsoons keeps the climate moderate and balmy.
The wind blows almost uninterruptedly throughout the year with quite a strength and the average wind speed seldom drops below 10 knots. This keep the summer heat of Zanzibar islands in check.
In short the Zanzibar islands are worth visiting for their temperate climate and moderate rainfall by equatorial standards.