Ghana has three hydro-climatic zones. The South-Western system is the most humid part of the country, with mean annual rainfall between 1500 mm and 2000 mm. The Volta basin system, covering the northern part of the country, has mean annual rainfall of about 1000 mm in the savanna area and about 1500 mm to 2000 mm in the forest area. The Coastal basin system is the driest, with mean annual rainfall of about 900 mm. Ghana’s climate is tropical and strongly influenced by the West African monsoon. Seasonal variations in temperature in Ghana are greatest in the north, with highest temperatures in the hot, dry season (April, May, and June) at 27‐30°C; further south, temperatures are lower (June, August, September) at 22‐25°C.

Temperature

• Mean annual temperature has increased by 1.0˚C , at an average rate of 0.21˚C per decade since 1960. The rate of increase has been higher in the northern regions of the country than in the south.
• The average number of ‘hot’ days per year increased by 48 between 1960 and 2003.
• The average number of ‘cold ‘days per year decreased by 12 (3.3% of days) between 1960 and 2003.

Precipitation

• Rainfall over Ghana was particularly high in the 1960's, and decreased to particularly low levels in the late 1970's and early 1980's, producing an overall decreasing trend in the period 1960 to 2006, with an average precipitation of 2.3mm per month (2.4%) per decade.
• There is no evidence of a trend in the proportion of rainfall that has occurred in ‘heavy’ events since 1960.

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