Climate & Soils
In general the climate of Zanzibar is shaped very much by the trade winds of the tropical Monsoon system. From April to October there is Southwest Monsoon or Kusi, literally meaning southerly in Swahili, and Northeast Monsoon or Kaskazi, literally meaning southerly in Swahili from November to March.
The rainfall pattern is bimodal in nature, with a long rainy season (Masika) from mid March to end of May and short rains (Vuli) within the months of October to December. Comparing the two islands, Pemba on average receives more rainfall (1900mm) than Unguja (1600mm). The distribution of rainfall is such that there is more rainfall in the western sides than the east.
Temperatures in Zanzibar are high during the short dry season of January to February, with maximum mean of 32°C, and low during the cool season lasting from May to September. The cool season, also known as Kipupwe in Swahili may be associated with periods of scattered showers called Mchoo in Swahili. The mean annual maximum and minimum temperatures are 29.3°C and 21.1°C, respectively.
The relative humidity is high, with a monthly average ranging from 87% in April (Masika) to 76% in November (Vuli), and a minimum at 60% during the dry season. Therefore, with humidity values in the range of 80%, daily temperatures can sometimes be as high as 40°C particularly in the night when the land is braced with hot breezes
According to earlier local classification based on physical characteristics, soils of Zanzibar can be categorised into upland soil types differentiated by geomorphology and lowland soils whose parent material forms the basis for classification. In general, soils of the western side of both Unguja and Pemba are deeper than those of the eastern side.