is low, and average rainfall varies from almost zero in the coastal desert to more than 600 mm in the Caprivi Strip. Rainfall is highly variable, and droughts are common.[49] The last[update] bad rainy season with rainfall far below the annual average occurred in summer 2006/07.[50]Weather and climate in the coastal area are dominated by the cold, north-flowing Benguela current of the Atlantic Ocean, which accounts for very low precipitation (50 mm per year or less), frequent dense fog, and overall lower temperatures than in the rest of the country.[49] In Winter, occasionally a condition known as Bergwind (ජර්මන්: Mountain breeze) or Oosweer (Afrikaans: East weather) occurs, a hot dry wind blowing from the inland to the coast. As the area behind the coast is a desert, these winds can develop into sand storms, leaving sand deposits in the Atlantic Ocean that are visible on satellite images.[51]The Central Plateau and Kalahari areas have wide diurnal temperature ranges of up to 30 °C