When is best to book your safari holiday of a lifetime?

Kenya

JAN-MAR and JUL-OCT: Dry seasons so animals are easier to spot in the lesser vegetation and watering holes are highly frequented. 
APR, MAY and NOV: Shoulder seasons, best for value whilst still offering opportunities to spot a plethora of flora and fauna. 
JUL-OCT: The annual migration crosses the Maasai Mara following the rains. 
OCT-NOV: Particularly good birding months, especially at the Kenyan Lakes.

Tanzania

JAN and JUN-OCT: The dryer months so low vegetation and busy watering holes. January is particularly hot. 
JAN-MAR and SEP-OCT: The best time to climb Mount Kilimanjaro. 
NOV-MAY: Annual migration circles the Serengeti. Between December and March is the birthing season.

South Africa

MAR: Best time to travel to catch the tail end of the summer but avoiding the crowds in the game parks. 
MAY-AUG: Vegetation is at its thinnest so game is easy to spot, rainfall is minimal and the temperature is warm. 
MAY-NOV: Whale watching off the coast as southern right and humpback whales come to mate, calve and rear their young in the warm waters.

Botswana

MAY-NOV: Dry season so grasses are low and animals congregate at water sources. October is the hottest month. 
SEP-OCT: Herds of elephant and buffalo start forming in Chobe National Park. 
DEC-MAR: Wet season so is it less busy in the parks. Shoulder seasons are December and March. Botswana is beautiful and green during the wet season and the birding is outstanding. This is also the period of birthing for all the grazing animals.

Namibia

MAY-SEP: Great time to visit Sossusvlei or the Etosha National Park as the temperatures are tolerable and animals are seeking water. Temperatures can drop at night in the desert. 
OCT-MAR: Best time for stays in the Namib-Naukluft as the coastal setting keeps it cooler than the interior of the country, however it can still be very hot. 
OCT-APR: Better for birding in Etosha National Park and the Etosha Pan fills with birds including flocks of flamingos at this time of year. However be careful as temperatures can get very high.

Zambia

APR-MAY: Best time to visit Victoria Falls as they are at their fullest. For those who wish to indulge in white water rafting, visit later in the year. 
JUN-OCT: Dry season so best time to spot wildlife. September and October are the driest so permanent water sources will be busy. 
DEC-APR: Great for birding as everything is flourishing in the rains providing lots of berries and insects.

Rwanda

JUN-SEP and DEC-FEB: Dry season, though light rains are prevalent all year round due to the tropical climate. 
JAN-MAR and SEP-OCT: This is the wet season, so rains and mosquitos are frequent. However, this is the best time for photographers as the air is generally clearer and better suited for photos.