The climate of Africa, more than that of any other continent, is generally uniform. This results from the position of the continent in the Tropical Zone, the impact of cool ocean currents, and the absence of mountain chains serving as climatic barriers. Seven main African climatic zones can be distinguished.
The central portion of the continent and the eastern coast of Madagascar have a tropical rain forest climate.
Here the average annual temperature is about 26.7° C (about 80° F), and the average annual rainfall is about 1780 mm (about 70 in). The climate of the Guinea coast resembles the equatorial climate, except that rainfall is concentrated in one season; no months, however, are rainless.
To the north and south the rain forest climate is supplanted by a tropical savanna climate zone that encompasses about one-fifth of Africa. Here the climate is characterized by a wet season during the summer months and a dry season during the winter months. Total annual rainfall varies from 550 mm (20 in) to more than 1550 mm (more than 60 in). Away from the equator, to the north and south, the savanna climate zone grades into the drier steppe climate zone.
Average annual rainfall varies between 250 and 500 mm (10 and 20 in) and is concentrated in one season. Africa has a proportionately larger area in arid, or desert, climate zones than any continent except Australia. Each of these areas-the Sahara in the north, the Horn in the east, and the Kalahari and Namib deserts in the southwest-has less than 250 mm (less than 10 in) of rainfall annually.
In the Sahara, daily and seasonal extremes of temperatures are great. The average July temperature is more than 32.2° C (90° F); during the cold season the nighttime temperature often drops below 0° C (32° F). Mediterranean climate zones are found in the extreme northwest of Africa and in the extreme southwest. These regions are characterized by mild, wet winters and warm, dry summers.
In the highlands of eastern Africa, particularly in Kenya and Uganda, rainfall is well distributed throughout the year, and temperatures are equable. The climate on the high plateau of southern Africa is temperate.