The Collaborative International Dictionary of English v.0.48:

Meteoromancy \Me`te*or"o*man`cy\, n. [Meteor + -mancy : cf. F.
   m['e]t['e]oromancie.]
   A species of divination by atmospheric phenomena, chiefly by
   thunder and lightning, which was held in high estimation by
   the Romans.
   [1913 Webster]