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Climate

The Sahel has a tropical semi-arid climate (Köppen climate classification BSh). The climate is typically hot, sunny, dry and somewhat windy all year long. The Sahel's climate is similar to, but less extreme than, the climate of the Sahara desert located just to the north.

The Sahel mainly receives a low to very low amount of precipitation annually. The steppe has a very long, prevailing dry season and a short rainy season. The precipitation is also extremely irregular, and varies considerably from season to season. Most of the rain usually falls during four to six months in the middle of the year, while the other months may remain absolutely dry. The interior of the Sahel region generally receives between 200 mm and 700 mm of rain yearly. A system of subdivisions often adopted for the Sahelian climate based on annual rainfall is as follows: the Saharan-Sahelian climate, with mean annual precipitation between around 100 and 200 mm (such as Khartoum, Sudan), the strict Sahelian climate, with mean annual precipitation between around 200 and 700 mm (such as Niamey, Niger) and the Sahelian-Sudanese climate, with mean annual precipitation between around 700 and 900 mm (such as Ouagadougou, Burkina Faso). The relative humidity in the steppe is low to very low, often between 10% and 25% during the dry season and between 25% and 75% during the rainy season. The least humid places have a relative humidity under 35%.

The Sahel is characterized by constant, intense heat, with an unvarying temperature. The Sahel rarely experiences cold temperatures. During the hottest period, the average high temperatures are generally between 36 and 42 °C (97 and 108 °F) (and even more in the hottest regions), often for more than three months, while the average low temperatures are around 25 to 31 °C (77 to 88 °F). During the "coldest period", the average high temperatures are between 27 and 33 °C (81 and 91 °F) and the average low temperatures are between 15 and 21 °C (59 and 70 °F). Everywhere in the Sahel, the average mean temperature is over 18 °C (64 °F).

The Sahel has a high to very high sunshine duration year-round, between 2,400 hours (about 55% of the daylight hours) and 3,600 hours (more than 80% of the daylight hours). The sunshine duration in the Sahel approaches desert levels, and is comparable to that in the Arabian Desert, for example, even though the Sahel is only a steppe and not a desert. The cloud cover is low to very low. For example, Niamey, Niger has 3,082 hours of bright sunshine; Gao, Mali has near 3,385 hours of sunshine; Timbuktu, Mali has 3,409 sunny hours, and N'Djamena, Chad has 3,205 hours of sunlight.