Both Tanzania’s climate and wildlife viewing opportunities are primarily driven by the East African rains. It’s the rains which trigger the mass movement of up to two million wildebeest, zebra, and impala from the Ngorongoro Crater into the Serengeti during the annual Great Migration. Although year-round, the best time to witness this spectacle is at the crossing of the Grumeti and Mara rivers between July and September, when temperatures are also at their coolest (averaging 76°F/25°C). Needless to say, these three months see the majority of travelers to Tanzania as a result. Many combine tours of Tanzania’s northern or southern safari circuits with summitting Mount Kilimanjaro – Africa’s highest peak – or a few days on the beaches of Zanzibar. Diving is possible throughout the year here, with visibility best in July and August and whale sharks visiting from September through December. An impressive array of wildlife, including the Big Five, can still be admired on safari in Tanzania at other times of year. The period from November through March comes with the risk of showers (usually for a couple of hours in the afternoon). Yet at the same time, you’ll encounter the migration’s newly-born calves, alongside the predators which stalk them. The birding is also at its best, as migratory species visit Tanzania.