The best time to embark on a safari in Tanzania and Kenya typically extends from mid-June to late October, reaching its peak in August and September. This window of approximately four to five months falls between East Africa's rainy seasons and offers the best weather conditions and the most exhilarating game viewing experiences.

At the beginning of June, the Great Wildebeest Migration commences its journey towards the western Serengeti, ultimately encountering the swollen Grumeti River, teeming with crocodiles, as they seek access to the region's grassy plains. The herds rapidly consume the available resources, compelling their migration northward toward the Masai Mara by late July and early August.

To reach the lush grazing grounds there, they face another challenging river crossing, this time across the Mara River. Once safely across, they remain in the Mara until early October before commencing their journey southward, feeding along the way towards their next destination.

Across Kenya and Tanzania, the arid conditions caused by the absence of rain result in increasingly dry and open savannahs. This improves visibility and draws wildlife to the water sources. In Southern Tanzania, visitors can enjoy a unique and isolated safari experience by cruising the Rufiji River delta by boat. Alternatively, in northern Kenya, exploring the banks of the Ngiro River offers exceptional elephant viewing, arguably among the finest in Africa.

This period also presents an opportune time for a combined safari and beach vacation, as the weather on the beaches of the Kenyan south coast and the Tanzanian islands of Zanzibar and Pemba is stable, comfortable, and less humid.

It's important to note that this time frame corresponds with the peak season, resulting in higher prices and some degree of crowding (albeit relative in the vast African wilderness) in certain popular destinations.