Including a description of the climate and weather of Burkina Faso, Niger, and Chad in the Sahel belt of interior West Africa.
Mali has a climate which is very similar to that found in three other countries of interior West Africa: Burkina Faso, Niger, and Chad.
These four countries all lie on the southern side of the Sahara desert, in what is called the Sahel belt. Only Burkina Faso does not extend far enough north to include part of the Sahara desert within its borders. The general features of the weather and climate of all four countries are described here.
These countries are landlocked and lie in a belt between 25° and 10°N. In the south of this belt annual rainfall is about 1,000 mm/40 in a year and this decreases northwards to virtually nil in the Sahara. Effectively the desert border is at about 15°N, where annual rainfall is about 400 mm/16 in.
The length of the rainy season and the reliability of the rain also decrease from south to north. The rainy season here is the period of high sun from May until September, with the heaviest and most reliable rains coming in July and August.
The period from November until March is virtually rainless everywhere. This is the dry season with warm to hot, sunny days with persistent northeasterly winds (the harmattan). The arrival of the rains is heralded by light to variable winds and then, when the rains arrive, the winds become persistently west to southwest. These winds bring cloudy and more humid air from the equatorial regions of the South Atlantic.
Temperatures are highest from March to May before the change of wind direction. Much of the rain occurs in heavy downpours associated with thunder squalls which are more likely to occur in the afternoon or evening and to die out at night.
Some longer spells of light rain or drizzle occur, however. Humidity is low during the very hot period before the arrival of the rains. Although the heat can be fierce and impose some stress at this time, it is no more unpleasant than the slightly cooler but more humid conditions during the rainy season.
The weather and climate of the northern part of this region are typical of the Sahara desert: very hot and dry during the period of high sun from May until September; rather cooler but still very warm and persistently sunny during the period of low sun.
Any rare and sporadic rainfall is likely to occur during the hottest season as occasional thunderstorms break out when the rain-belt is at its most northerly position.
Mali is the most westerly of these four countries. It has an area rather larger than Egypt and is sparsely populated except in the south. About half of Mali lies in the southern Sahara and is virtually rainless.
Climate and weather here are represented by the table for Faya in Chad. The table for Tombouctou shows conditions in central Mali at the northern limit of the summer rain-belt. This table shows the reduction in temperature and the increase of humidity in July after the arrival of the rains.
The table for Bamako shows the heavier rainfall and longer rainy season experienced in the south of the country. When the harmattan is strong it is often dust-laden and this, combined with high temperatures and very low humidity, can be unpleasant.
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