Best months to climb Mount Kilimanjaro are considered to be August to October and January to March.
The climate is tropical on the coast, on the islands and in Selous. It is temperate in the other parks. Temperatures on Mount Kilimanjaro and Meru drop to below freezing.
Late March – Late May: is traditionally the long rainy season. This period is considered the “winter period” in Tanzania.
June – Late October: is the dry season. June, July and August can be very cold on the rim of Ngorongoro Crater. The Islands are lovely at this time of year, the evenings are cool (not Cold) and the daytime hot.
Late October – Mid December: is when the short rains occur. These tend to be in the form of a daily thunderstorm. The Ngorongoro Crater rim has a wonderful climate at this time of year. The Serengeti and Lake Manyara are very warm and the Islands are very hot.
Mid December – March: is summer weather. It is dry and very warm until March. Due to its altitude Ngorongoro Crater is much cooler than elsewhere.