The Collaborative International Dictionary of English v.0.48:

Drouth \Drouth\, n.
   Same as Drought. --Sandys.
   [1913 Webster]

         Another ill accident is drouth at the spindling of
         corn.                                    --Bacon.
   [1913 Webster]

         One whose drouth [thirst],
         Yet scarce allayed, still eyes the current stream.
                                                  --Milton.
   [1913 Webster]

         In the dust and drouth of London life.   --Tennyson.
   [1913 Webster]

WordNet (r) 3.0 (2006):

drouth
    n 1: a prolonged shortage; "when England defeated Pakistan it
         ended a ten-year drought" [syn: drought, drouth]
    2: a shortage of rainfall; "farmers most affected by the drought
       hope that there may yet be sufficient rain early in the
       growing season" [syn: drought, drouth]