As Tanzania is only a little south of the equator, there are no major temperature fluctuations
noticeable between the seasons. In general, the climate in Tanzania is considered tropical. However, there is a small and a big rainy season between the dry periods. The small rainy season from mid / end of October to the end of November generally affects the journeys only slightly, but the large rainy season from mid-March to the end of May makes some areas and national parks of Tanzania partly impassable.
Tanzania is a year-round destination, but this applies due to the size of the country, the difference between inland and coastal climates as well as the different heights of the country. The ideal travel time is therefore dependent on your specific destination and the planned activities.
For the north roughly the following rule of thumb is valid, which however may differ because of the progressive climate change:
The ideal travel times lie in the dry months from December to March and from June to October. From December to March there are good visibility conditions, the climate can be very hot and there is hardly any precipitation. From June to October the temperatures are quite pleasant. The high season for safaris is in July and August during the migration of the animals.
The Kilimanjaro can, in principle, be climbed year-round, but during the great rainy season this is only recommended to a limited extent (for example, on the Rongai route), but a climb up Mount Meru is not recommended for "normal" mountain walkers. The best months to climb the Kilimanjaro are January and February, however most of the summit climbs take place here.