Source : Webster's Revised Unabridged Dictionary (1913)

Southwester \South`west"er\ (?; colloq. ?), n.
   1. A storm, gale, or strong wind from the southwest.

   2. A hat made of painted canvas, oiled cloth, or the like,
      with a flap at the back, -- worn in stormy weather.

Source : WordNet®

southwester
     n : a strong wind from the southwest [syn: {sou'wester}]