Lake Turkana is situated in the Great Rift Valley in the north-western part of Kenya. It is in an arid and hot area. The mean annual rainfall in most of the lake surroundings is less than 250mm. the occurrence of rainfall is very erratic and unpredictable, although the probability of rainfall in the highest during the “long rain” in March/May. The air temperature recordings at Lodwar show a seasonal pattern with the lowest temperature in July/August, a wide range between 19,5º and 39,9ºc, and a mean daily temperature of 29,26ºc. The lake is exposed to frequent strong winds, the prevailing wind direction being from the southeast. Lake Turkana has no outlet, and water is lost from the lake mainly by evaporation.