When rain comes down in buckets, there's an old phrase that seems to fit perfectly: "It's raining cats and dogs." We learn it as kids and never think twice. But it's a strange picture when you stop to imagine it. Why would anyone describe a storm with household pets?
The honest answer is that nobody knows for sure. The phrase means very heavy rain, and a version of it, with "polecats" instead of cats, has been used since at least the 1600s. Several theories try to explain it, but none has been proven. It's also not necessarily connected to real cases of animals falling from the sky.
Theory One: Messy City Streets
One explanation points to the poor drainage on buildings in 17th-century Europe. During heavy storms, gutters and drains could overflow and wash out whatever had collected in them, sometimes including dead animals.
Jonathan Swift described exactly this kind of mess in his 1710 poem "Description of a City Shower," where a London downpour sweeps all sorts of grim debris through the streets. It's not proof of the phrase's origin, but it shows how a storm and stray animals might have been linked in people's minds.
Theory Two: A Garbled Old Word
Another idea is that "cats and dogs" is a mangled version of an old word for a waterfall. The ancient Greeks called the waterfalls on the Nile Katadoupoi, and an old French word, catadupe, meant waterfall. In old English, catadupe meant a cataract or waterfall too. Rain like a waterfall would certainly fit. Still, it's only a theory.
One language scholar suggested the Greek expression kata doxa, meaning "contrary to belief," but he also noted there's no evidence English speakers ever borrowed it.
There's also a 1592 sentence that complains of a storm that "shooteth nothing but dogboltes or catboltes" instead of thunderbolts. Dogbolts and catbolts were types of iron and timber bolts. The phrase might be a shortened echo of that.
The Myth About Thatched Roofs
You may have seen a story passed around by email: that in the 1500s, cats and dogs crawled into the thatched roofs of peasant homes to stay warm, then slid out during heavy rain. It sounds clever, but no evidence has been found to support it. It's a good example of how a tidy explanation can spread fast.
The simplest answer may be the right one. The phrase might just be silly on purpose, like other old expressions for a downpour such as "raining pitchforks" or "raining hammer handles."
When Animals Really Do Fall
Here's a strange twist. Animals have actually been reported falling from the sky, usually frogs or fish. In 1794, French soldiers reported toads falling during heavy rain near Lille. In 1987, people in three English towns reported tiny pink frogs coming down with the rain. In Yoro, Honduras, locals say a "rain of fish" happens every summer. Back in the Middle Ages, fish rains were reported so often in certain areas that some people imagined fish were born in the sky.
One scientific idea is that waterspouts, tornadoes that form over water, scoop up small creatures and drop them miles away. Scientists have never actually witnessed it happening, though. So next time the sky opens up, you can say it's raining cats and dogs with confidence. Just be glad it isn't raining frogs.
