“It’s Raining Cats and Dogs” is an idiom meaning it’s raining intensely.
“I’m afraid the river will flood. It’s raining cats and dogs out there!”
Where did it come from?
As with many idioms because they’ve been around so long, the definitive origin is lost in time. There are a few speculations, from Norse gods and witches to cats and dogs being washed from thatched roofs in medieval times. Here are the theories:
Theory #1: Odin, the Norse god of storms, was often pictured with dogs and wolves, which were symbols of wind. Witches, who supposedly rode their brooms during storms, were often pictured with their familiars, black cats. This became signs of heavy rain for sailors. Therefore, “raining cats and dogs” may refer to a storm with wind (dogs) and heavy rain (cats). Unlikely.
Theory #2: “Raining cats and dogs” may come from the Greek expression cata doxa, which means “contrary to experience or belief.” If it is raining cats and dogs, it’s raining unusually or unbelievably hard. Unlikely.
Theory #3: Cats and dogs, supposedly, used to cuddle into thatch roofs during storms and were washed out during heavy rains giving the appearance of “raining cats and dogs.” Again, unlikely.
Theory #4: “Cats and dogs” may be an adaptation of the now obsolete word catadupe. In old English and many of the old languages, catadupe meant a cataract or waterfall. In Latin, catadupa was borrowed from the classical Greek κατάδουποι, which referred to the cataracts of the Nile River. It’s said because of this rain falling hard like a waterfall was associated with “cats and dogs.” Still a stretch.
Theory #5 and most likely the true source of “raining cats and dogs” comes from 17th century England. It wasn’t uncommon to witness dead strays, cats and dogs, being washed along the gutters during heavy rains along with other debris.
In 1653, in a comedy by Richard Brome, The City Wit or The Woman Wears the Breeches, a similar term was coined:
“It shall raine… Dogs and Polecats”.
A polecat is actually a weasel and not a cat at all, but it’s thought this was an early form.
Jonathan Swift’s A Complete Collection of Polite and Ingenious Conversation in 1738 is thought to be the first literary appearance of the phrase as it’s used now:
“I know Sir John will go, though he was sure it would rain cats and dogs”.
Swift had alluded to the streets running with dead cats and dogs during heavy rain a few years earlier, so it’s fair to presume this was where his metaphor came from. It’s kind of gruesome, but there you have it!