What is the harmattan season in western Africa?

The harmattan is a cool, dry, and gusty trade wind that blows from the northeast or east across the western Sahara and into western Africa. It is most prevalent during the cooler months, typically from late November to mid-March.12

Key characteristics of the harmattan include:

• Atmospheric Conditions: It is an extremely dry air mass that often carries large amounts of dust. This dust can travel hundreds of kilometers over the Atlantic Ocean, frequently disrupting aircraft operations and settling on ships.1
• Temperature Variations: While the wind can feel cool—especially at night or due to its effect of evaporating moisture from human skin—it is characterized by extreme daily heating, often resulting in a significant daily temperature range. In some areas, temperatures may drop as low as 9 °C (48.2 °F).21
• Monsoonal Interaction: The harmattan is a component of the West African monsoon, alternating with the moist, southwesterly monsoon winds. During the summer, the harmattan is forced to higher altitudes by the cooler, humid monsoon flow.21