The climate is tropical and humid, with little change in temperature throughout the year. The mean is 27° C (81° F ), with temperatures rarely exceeding 36° C (97° F ) or falling below 20° C (68° F ). On the coast the heat is tempered by an almost constant breeze. Yearly rainfall is as high as 510 cm (200 in) on the coast, decreasing to about 200 cm (80 in) in areas farthest inland. There are distinct wet and dry seasons, most of the rainfall occurring between late April and mid-November. Average relative humidity in the coastal area is about 82% during the rainy season and 78% in the dry, but it may drop to 50% or lower between December and March, when the dust-laden harmattan blows from the Sahara.