The dry east wind known as the harmattan blows intermittently from December to March.
During the dry season, when the climate is very much like that of the West Indies, there occur terrible tornadoes and long periods of the harmattan - a north-east wind, dry and desiccating, and carrying with it from the Sahara clouds of fine dust, which sailors designate "smokes."
The mean temperature in the dry season, when the "harmattan" is frequent, is 62° Fahr., in the wet season 86°.
Known in Egypt as the khamsin, on the Mediterranean as the sirocco, it is called on the Guinea coast the harmattan.
The dry wind from the Sahara called harmattan, which carries great quantities of fine red sand, causes a fall of temperature in the (European) summer.