The general legend about “raining cats and dogs” relates to the thatched roofs of the Middle Ages.
It would have you believe that when it rained, all sorts of creatures, including cats and dogs, slipped and fell in such abundance that it gave rise to the expression, but that’s wrong.
The truth is that the saying predates even the Dark Ages and goes back to a time when people believed that ghosts and goblins were around every corner.
Cats and dogs had magical, mystical powers.
Sailors believed that cats brought on storms and that witches rode those storms (with their cats).
To the early Norsemen, dogs and wolves symbolized the wind, and the Viking storm god Odin was always shown surrounded by dogs.
So during a violent rainstorm, an angry Odin’s dogs were set loose, and the cats, symbolizing the rain, caused people to say, “It’s raining cats and dogs.”
The word cat is derived from the ancient Greek word catadupe and means “waterfall.”
In Latin cata doxas means “contrary to experience,” or “an unusual fall of rain.”