From Gurunet:
har·mat·tan (här'mə-tăn', här-măt'n)
n.
A dry dusty wind that blows along the northwest coast of Africa.

[Akan (Twi) haramata, possibly from Arabic ḥarām, evil thing, from ḥarama, to prohibit.]

Yes, welcome, Sonnie; we've not had a person posting from Nigeria before--that I knew of, anyway. Cool!

(Dang--just previewed; sorry about the numbers; dunno what to do about them other than delete, which would leave something to be desired in the copy I think.)