raining cats and dogs

The popular story

The best-known explanation comes wrapped in cosy period detail. In the old days, it is said, cottages had thick thatched roofs in which household animals — cats, dogs, even mice and rats — liked to shelter for warmth. When heavy rain came, the thatch grew slippery and the animals slid off, or were washed down, so that it seemed to be “raining cats and dogs”. The tale usually arrives as part of a long list of supposed facts about life in earlier centuries.

A grimmer cousin of the story sets the scene in filthy city streets, where torrential rain swept the bodies of drowned strays through the gutters, giving onlookers the impression that the animals had fallen from the sky.

What the record shows

Neither picture survives inspection. Animals do not shelter on the outside of a thatched roof, where they would be exposed to the very weather they were escaping; and a properly made thatch is steeply pitched and water-resistant, precisely so that rain runs off rather than soaking through. The idea that pets routinely tumbled from the eaves in every storm is a modern embellishment, and it is not found in any early source explaining the phrase.

The phrase itself is old. Its modern wording is recorded in Jonathan Swift’s satirical A Complete Collection of Polite and Ingenious Conversation (1738):

I know Sir John will go, though he was sure it would rain cats and dogs.

An earlier and looser variant appears in Richard Brome’s play The City Wit, printed in 1653, with the line that it shall “raine… Dogs and Polecats”. These citations place the expression firmly in the seventeenth and early eighteenth centuries — but crucially, none of them explains why cats and dogs. They simply use the phrase as an already familiar figure for a violent downpour.

The street-washing version has a grain of atmosphere to it: Swift himself, in a separate poem, “A Description of a City Shower” (1710), pictures filth and drowned animals swept along the flooded gutters of London. But describing a squalid storm is not the same as coining the phrase, and there is no evidence that his vivid scene gave rise to the idiom rather than merely sitting near it.

The verdict

This is folk-etymology, layered over a real mystery. The thatched-roof story is a modern invention, unsupported by early evidence and contradicted by how thatch actually works. What it has displaced, however, is not a tidy true origin but an honest blank: the phrase is old and well attested, yet the reason for its striking image is not known.

What we don’t know

The true source of the imagery is genuinely undetermined. Several guesses circulate, none of them proven. One derives it from the Greek expression kata doxa, “contrary to belief”, suggesting rain so hard it beggars belief. Another looks to an old French word, catadoupe, meaning a waterfall or cataract. A third reaches for Norse storm imagery, in which dogs were associated with wind and cats with rain. Each is ingenious; each lacks supporting evidence, and the sound-alike theories in particular have the look of explanations invented to fit the phrase rather than sources it actually grew from. The most reputable authorities conclude plainly that the origin is unknown.

The likeliest account is also the least dramatic: that the phrase began as sheer vivid exaggeration, an absurd image for an absurd amount of rain, in the same spirit as “raining pitchforks” or the French “il pleut des cordes” (“it’s raining ropes”). Cats and dogs, proverbially at odds with one another, may simply have suggested noise, chaos and fury — a sky at war with itself. That is a plausible instinct rather than a documented origin, and honesty requires keeping the two apart.

It is worth adding that animals very occasionally do fall with rain: waterspouts and violent updraughts have been known to lift fish or frogs from a pond and drop them some distance away. This is a real if freakish phenomenon, but it involves small aquatic creatures, not cats and dogs, and it has nothing to do with the origin of the expression.

How it changed

From its seventeenth-century beginnings the phrase has stayed remarkably stable in both form and meaning, settling into the fixed modern wording seen in Swift. What has shifted is only the mythology around it: as the original sense of the image faded, listeners reached for concrete explanations, and the thatched-roof story eventually filled the gap, spreading widely through trivia lists and forwarded emails.

Usage today

The expression is still an everyday way to describe a heavy downpour: “bring an umbrella — it’s raining cats and dogs out there.” It is used with no thought of literal animals, which is fitting, because there never were any. The honest position is the interesting one: a phrase we have said for centuries, whose picture nobody has ever quite explained.

That candour is the point of an entry like this. It would be easy to pick one of the sound-alike theories and present it as the answer, and many popular accounts do exactly that. But a guess dressed up as a fact is worth less than a clearly labelled unknown. What can be stated with confidence is a good deal: the phrase is old, it is recorded from the seventeenth century, its wording settled early, and its most famous “explanation” — the sliding animals of the thatched roof — is a modern fiction. What cannot be stated is why the English chose cats and dogs to stand for a cloudburst. On that, the most reliable authorities agree, the truest answer remains: we do not know.