The Nile River Basin has two types of climate. In the northern half, where Egypt and Sudan are, there is less than five inches of annual rainfall. In the southern half, they have heavy rains in the summer months, averaging 40-60 inches per year. Between October and May both regions are dry, due to northeast trade winds. There are regions in eastern Africa that have more of a tropical climate. The rainy season is considered to be from April to October. The temperature may be from 60º F to 80º F, with the humidity around 80%. Heavy rain in central Africa, as much as 80 inches per year, causes the Nile to rise every year.