From Darwin, in the voyage of the beagle:
"From the direction of the wind whenever it has fallen, and from its having always fallen during those months when the harmattan is known to raise clouds of dust high into the atmosphere, we may feel sure that it all comes from Africa."
Another wind name for you, WW.
harmattan
n.
5Sp harmat;n < the native (Twi) name in W Africa6 a dry, dusty wind that blows from the Sahara in N Africa toward the Atlantic, esp. from Nov. to March