Tanzania is located a few degrees south of the equator and has a tropical climate, influenced mainly by its altitude. The main rainy season (called masika in Kiswahili) is in April and May, and typically there is heavy rain (especially in the afternoon) which is more regular on the coast than it is inland. June to October is certainly the driest time, with cooler temperatures than the rest of the year. The south wind, known as the kusi, keeps the islands and the coast breezy. The long dry season is followed by the short rains or mvuli, usually from mid-November to early December, during which the rains are scanter and more sporadic than during the masika. The shorter rainy season is followed by another dry season, lasting from late December to late March. During this time temperatures are higher than they are from June to October and there are occasional showers.
In general, the Northern Highlands enjoy lower temperatures and less humidity than the coastal lowlands and the islands.