Northern Benin has a dry season and a wet season that are controlled by the movement of the Inter-tropical Convergence Zone (ITCZ). The rainy season lasts from May-November when the ITCZ is in its northern position. The dry season is from December-March when the ‘Harmattan’ winds blow in from the northeast bringing air from the Sahara Desert. Northern and central Benin receive between 200-300 mm of rainfall per month during the height of the rainy season (July-September). Southern Benin experiences two wet seasons differing in length and coinciding with the northern and southern passages of the ITCZ across the region. The longer rainy season occurs from March-July and the shorter one from September-November. Southern Benin experiences great variability in its seasonal rainfall from year to year and decade to decade. 

Temperature

• Mean annual temperature has increased by 1.1°C with the rate of increase most rapid in the months of April-June.
• Temperatures over West Africa have risen with greater magnitude during the latter 20 years of the period from 1970-2010 than the former.

Precipitation

• Annual rainfall in Benin is highly variable on annual and decadal timescales, making it difficult to determine long-term trends. No trend in mean annual precipitation has been detected over 1960-2006.
• Drier and rainier periods are detected over 1960-2006; the early 1960's to 1980's saw drier years than the 1980's to present.
• April-June rainfall decreased consistently from 1960-2006 with an average rate of decrease of 3.9 mm per month per decade, which affected southern Benin the most.
• Increasing variability in the rainy season has been observed and characterized by a shortening of the rainy season. In the interior of Benin, rainfall has decreased whereas the coastal zone has seen an increase.

This section provides the options to visualize historical climate data for different timeframes via map and annual cycle chart.