Idiom: Raining cats and dogs
OED Definition: Rain very hard
Example: You had better take an umbrella with you, it’s raining cats and dogs
As with many of the idioms we have already seen, the origins of this one are somewhat unclear. The phrase has been in common use since 1651 when a similar phrase was used by British poet Henry Vaughan in the collection of poems Olor Iscanus. Since then, several other versions of the saying have been used to describe downpours of heavy rain, for example, ‘It’s raining pitchforks’ or ‘It’s raining stair-rods’. However, neither of these have proven to be as popular as ‘Cats and dogs’.
Although there is no clear explanation of where this idiom has come from, several different theories have been offered. The first refers to mythology and Odin, the Norse god of storms. When represented in art, Odin is often pictured alongside dogs and wolves, which were symbols of strong winds. This is believed to be the ‘Dogs’ part of this expression. The ‘Cats’ part comes from belief in witchcraft, and the notion that witches and their black cat companions would ride around on broomsticks during large storms. Witches with black cats later became a warning signal to sailors that heavy rain was coming. Thus, ‘Raining cats and dogs’ might refer to a storm with both strong winds and heavy rain.
Another theory comes from the Greek expression ‘Cata doxa’ which roughly translates to ‘Contrary to experience or belief’. Therefore if it is ‘Raining cats and dogs’, the weather is unusual or unbelievably bad. An alternative to this is that ‘Cats and dogs’ have developed from the now obsolete French word ‘catadupe’. In old English, ‘catadupe’ was used to refer to a cataract or waterfall. So, ‘Raining cats and dogs’ might suggest that it is raining waterfalls.
The most common theory suggests that cats and dogs would huddle to the thatched roofs in order to seek shelter from the storm. If the weather was particularly bad, these animals would become dislodged from their hiding places and slip off the roof with the strong wind and heavy rain. However, this theory is often pooh-poohed as it relies on the animals being on the outside of the thatched roofs, clinging on for dear life. Many rightly point out that this would be extremely unlikely as it would serve as poor protection from a storm.
The most likely source of the expression is the fact that during the 17th century, the streets in England were extremely dirty and littered with all manner of things including dead animals. Therefore it has been suggested that the cats and dogs weren’t actually falling from the sky, but the sight of them being washed away by flood water was a clear indication of a bad storm.