There is no bad time to travel to Africa, but climate changes throughout the year – see climate charts in each destination– can alter wildlife movements and even the appearance of the landscape, so it is worth bearing these in mind.
The drier times of year can result in some of the best game-viewing, as thirsty animals are forced to come down to rivers and waterholes to drink. Some of the vegetation tends to die back, meaning smaller, shyer creatures can be easier to spot.
In contrast, the rainy season (or green season) can see a degree of wildlife dispersal, as animals can find food and water more easily. This is though a very beautiful time of the year, when the bush truly comes to life and many young animals are born. Migrant bird species also start to arrive.
Safari is a great way to get away from the city crowds of course – you will very often feel as though you have the wilderness to yourself. That said, the dry season tends to be the busier of the two seasons, so if you really want to get away from it all, you might want to try the green season. This is also often a good time of year to get special discounted rates.