Raining cats and dogs Informal

Raining extremely heavily, in a sudden, intense downpour.

It’s a vivid, informal way to describe bad weather, almost always used about rain specifically rather than other kinds of storms.

This is one of English’s most-discussed idioms precisely because no theory has ever achieved scholarly consensus. The earliest documented use appears in Richard Brome’s 1652 play “The City Witt,” with the line “It shall rain dogs and polecats,” already establishing the animal-based storm imagery a century before it’s most commonly attributed source. Jonathan Swift’s 1710 poem “A Description of a City Shower” is frequently credited as the origin, describing a flood that carries “dead cats and turnip-tops” through city streets, but since Brome’s citation predates it by over fifty years, Swift’s poem is better understood as reflecting an existing image rather than creating it. Other proposed explanations include a corruption of the rare Greek-derived word “catadupe” (waterfall), the debunked claim that thatched-roof cottages sheltered animals that would wash out in storms (no historical evidence supports this), and an obscure 1592 reference to “cat and dog bolts,” a type of iron fastener. None of these is considered proven, and some etymologists suspect the phrase may simply have caught on for its vivid, faintly absurd humor rather than any single traceable event or image.

We can’t go for a walk, it’s raining cats and dogs out there.

The picnic got cancelled because it started raining cats and dogs.

By the time we reached the car, it was raining cats and dogs.

A: Should we bring umbrellas? B: Definitely, it’s supposed to rain cats and dogs later.