While a majority of Senegal has a tropical climate, the country’s northern regions (located in the Sahel) are arid. The country experiences one long rainy season, which varies along a latitudinal gradient (north-south), from June/July to September/October, and is driven by the movement of the Inter-Tropical Convergence Zone (ITCZ). While the arid zones receive a rainfall total under 300 millimeters per year, the forested south receives an average of 1200 mm/year. Rainfall is highly variable both on the interannual and inter-decadal timescales. The average annual temperature for Senegal was 27.8°C for the period 1960-1990, with monthly averages in the hottest seasons of up to 35°C. Key historical climate trends are summarized below:
- Mean annual temperature has increased by 0.9°C since 1960, an average rate of 0.20°C per decade.
- Available data indicates that the average number of ‘hot’ nights per year increased by 27 (an additional 7.3% of nights) between 1960 and 2003.
- Sahelian rainfall is characterized by high variability on inter‐annual and inter‐decadal timescales, which can make long‐term trends difficult to identify. A period of particularly high rainfall occurred in the early 1960's, while the early 1980's were particularly dry. Statistically significant decreases of around 10 to 15 mm per decade have, however, been observed between 1960 and 2006 in the southern regions of Senegal (during the wet season of June through September).
- Some unusually high rainfalls have occurred in the dry season in recent years (2000‐2006), but this has not been part of a consistent trend.
- Senegal has experienced a statistically significant decrease in wet season rainfall between 1960 and 2006, with the 500 mm isohyets regressing about 100 kilometers (km) to the south.
This section provides the options to visualize historical climate data for different timeframes via map and annual cycle chart.