There are two seasons determining the agricultural cycle: the rainy season from May to November, and a dry season from December to May, which includes harmattan, when cool, dry winds blow in off the Sahara Desert and the night-time temperature can be as low as 16 °C (60.8 °F). The average temperature is 26 °C (78.8 °F) and varies from around 26 °C (78.8 °F) to 36 °C (96.8 °F) during the year. Average rainfall is highest at the coast, 3000-5000 mm per year, moving inland this decreases and at the eastern border of the country the average rainfall is 2000-2500mm.