This is a very relevant question which, as a Professional Field Guide, I have been asked countless times - and my answer remains pretty much the same.
Any time is great to experience an African safari.
Southern and Eastern Africa have a variety of different habitats and biomes – it is pretty much a guarantee that you will develop a seri
ous case of wanderlust when looking through photos, itineraries and suggested attractions.
One thing to certainly take into consideration is that Southern Africa is in the Southern Hemisphere – so the seasons are opposite with very short spring (September to November) and autumnal (March to May) seasons in comparison to the Northern Hemisphere. The winter (June to August) is much dryer and a little cooler (especially at night), whereas the summer (December to February) is hotter and more humid with spectacular thunderstorms.
So, as with any destination – seasons need to be taken into consideration when planning your trip. They are an important part in determining what you are likely to see and experience.
"Everything in Africa bites, but the safari bug gets you worst of all..."
If your trip is planned for spring/summer in the Southern Hemisphere. The African bush will be much fuller and greener with tall grasses, flowers, trees in full bloom and beautifully coloured migratory birds. You may also see lots of newly born animals; both the herbivores and carnivores – this is a very relaxing time to be in the bush with the flora and fauna all at their most impressive.
In comparison, the autumn and winter months are much dryer. But this isn’t necessarily a negative point. Far from it. The bush may be less green, but that means the wildlife will be more focused around water sources; improving your chances to see the Big Five or even Magnificent Seven (not the cowboys...). These seasons will give you a much clearer opportunity to view the wildlife and potentially see the rut, where the antelope species are battling for dominance against each other.
So in conclusion, there is no conclusive answer. Your trip to Africa should be planned around what you would like to experience. Perhaps speaking with friends or relatives which have been previously will give you a taster. Or speak to a reputable, experienced guide or organisation who will be more than happy to talk with you until your heart is content. Soon you'll be on your way and enjoying the life-changing experience that is going on a safari.