An Etymological Dictionary of the German Language/Annotated/Wetter
Wetter, neuter, ‘weather, storm, tempest,’ from the equivalent Middle High German wëter, Old High German wëtar, neuter; corresponding to Old Saxon wëdar, ‘weather, tempest, storm,’ Dutch weder, weêr, Anglo-Saxon wëder, English weather, and the equivalent Old Icelandic veðr (Gothic *widra- is wanting). If Teutonic wedro- is based on pre-Teutonic wedhro-, Old Slovenian vedro, neuter, ‘fair weather’ (vedrŭ, ‘bright, clear’), is related to it. It is possible, though less probable, that wetró- is the Aryan base, with which also Old Slovenian větrŭ, ‘air, wind’ (from the root wê, ‘to blow’), coincides. —