Sara and John say...
Lying close to the equator, Tanzania’s climate is tropical. So, when planning your visit, it would be natural to think of heat and humidity. That said, conditions do vary across the country with different regions having distinct seasons.
Much of the country sits at altitude, meaning temperatures are not as high as one might expect. Whether visiting Dodoma, the capital or journeying to the Serengeti, daytime highs are in the 20s rather than 30s Celsius for much of the year; and nights are comfortably cool, except in the steamiest summer months from December to March. The mountains, including Kilimanjaro, are, of course, even cooler.
The exception is the coastal plain, where it’s particularly hot and humid from November to April. Dar es Salaam, the former capital, is found here, where temperatures are close to 30 Celsius, even at the coolest time of year.
June to August tends to be the driest, sunniest and coolest period for much of the country - the perfect time for visiting, and that includes the islands of Zanzibar. There are two distinct rainy seasons. The ‘long’ rains are from March to May and the less reliable ‘short’ rains between October and December. Having said that, these periods vary across the country. For example, across parts of the south, the two can merge into one single longer wet season that continues through January and February.
Be aware, however, that the downpours are often intense but short-lived; and even in the peak of the wetter periods, there are several dry days.
So choose your month and pack accordingly to make the most of some of the most amazing wildlife on the planet!