The climate of Sierra Leone is tropical, with two seasons that determine the agricultural cycle. These seasons are the Rainy season that lasts from May to November and the Dry season from December to April. During the dry season there is a short spell of cool dry winds that blow in off the Sahara Desert. This period is refered to as harmattan period. At times during the night, temperatures can go as low as 16 °C (60.8 °F).