Tanzania experiences two rainy seasons, the heavier one being between mid-March to May (the masika rains) and the other in November, December and sometimes January (the mvuli rains). As stated above, though, don’t let this put you off travelling at these times of year! Otherwise, the climate of Tanzania is tropical, so warm and generally comfortable weather throughout the year is standard, with the coast experiencing higher levels of humidity than other areas.
Of course, the mountainous and highland areas of the country are cooler, with temperatures sometimes dropping below 15°C at night during June and July. In this area, it can rain at any time of year (usually in the early mornings if at all).
The island of Zanzibar also receives hot weather all year round, with temperatures ranging from 22-34°C or more. Zanzibar also experiences a rainy season between April-May, when downpours can be quite long and heavy. However, even during the rainy season, there are many burst of sunshine and sunny afternoons, and even whole days.