Northern Ivory Coast is part of the Sudanian Savanna ecoregion of the Tropical and subtropical grasslands, savannas, and shrublands biome. It is a zone of lateritic or sandy soils, with vegetation decreasing from south to north.[2] Temperatures average between 25 and 30 °C (77 and 86 °F). The main rainy season is between May and September, with the remaining part of the year being dry in the north of the country, as the Harmattan wind blows.