Average Annual Temperature
The African savanna has a relatively moderate temperature with it not going over 86° F and not going under 68° F. During the winter (which can pretty much be classified as the dry season) the temperature will range from about 68° F - 78° F (or 20° C - 25° C). During the summer (which is mostly acknowledged as the wet season) the temperature increases, ranging from 78° F - 88° F (or 25° C - 30° C.
Annual Rainfall
Nearly all of the precipitation in the African Savanna occurs during the wet season. During the wet season, which stretches from May to November, the savanna receives a total of around 100 inches of rain or about 20 inches per month (254 cm per dry season and 50.8 per month). During the dry season, there is a total of around only 4 inches throughout the entire season (or 10.16 cm).
Soil
Obviously during the wet season, the soil in the African Savanna is going to be wet and mushy but during the dry season it becomes very porous and dry. This leads to fires throughout the savanna and lots of plants and vegetation burn. However the ash from these blazes, re-joins the soil and adds nutrients back into it which help make the soil more fertile for the growth of vegetation.