An Etymological Dictionary of the German Language/Annotated/Schauer
Schauer (1.), masculine, ‘penthouse, shed’; see Scheuer.
Schauer (2.), masculine, ‘shower,’ from Middle High German schûr, Old High German scâr, masculine, ‘storm, hail’; compare Old Saxon skûr, masculine, ‘weather, shower,’ Dutch schoer, ‘pouring rain,’ Anglo-Saxon sčûr, English shower, and the equivalent Old Icelandic skúr; Gothic only skura windis, ‘gale.’ Origin obscure.