The largest individual Köppen climate zone in Africa is the Warm desert climate (BWh)
By Enhanced, modified, and vectorized by . - Derived from World Köppen Classification (with authors).svg., CC BY-SA 4.0, Link
The Warm desert climate (BWh) is the largest by area in Africa mainly because Africa happens to be generally wider in the north at latitudes 15 to 33 where the Sahara desert is. The wet topical centre is much narrower. In the south about as far from the equator as Sahara, there is the Kalahari desert. This is probably one reason why the population of Africa is only about 1.2 billion. About 15% of humanity lives in Africa while the land area is 20% of the Earth's total land area.