Tanzania Weather, climate and geography
The climate is tropical and coastal areas are hot and humid, while the northwestern highlands are cool and temperate. There are two rainy seasons; the short rains are generally from October to December, while the long rains last from March to June. The central plateau tends to be dry and arid throughout the year.
Tanzania can be visited year-round, although the best time for travelling is outside of the rainy season between June and October, when temperatures stay well below their summer peaks. Beach side locations like Zanzibar can be fine to visit during the hotter months of December to January, when ocean breezes make the high temperatures bearable (though humidity can still be high). However, this is also the time popular for typical beach holidays, especially for those travelling from Europe wanting some winter sunshine, and hotels can book up early especially for the Christmas and New Year period.
Tropical clothing is worn throughout the year, but in the cooler season, from June to September, jackets and sweaters may be needed, especially in the evenings. Clothing appropriate to temperatures below zero is required on the higher slopes of Kilimanjaro and Meru. Also note that it can get very cold at night on the rim of the Ngorongoro Crater and early morning game drives may be chilly before the sun comes up.