Of course, we all know that it isn’t possible for the clouds to open up and hurl household pets to the Earth. So why does the English language include this oddity?
One possible explanation for the figure of speech is that, during the Middle Ages, heavy rains caused the streets in England to flood. These “raging rivers of filth,” as Farmers’ Almanac contributing editor Richard Lederer described them, were generally filled with trash and waste, including the corpses of stray cats and dogs.
Lederer has also suggested that there may be a more folkloric explanation for the phrase:
In the dark Ages, people believed that animals, including cats and dogs, had magical powers. Cats were associated with storms, especially the black cats of witches, while dogs were frequently associated with winds. The Norse storm god Odin was frequently shown surrounded by dogs and wolves. So when a particularly violent storm came along, people would say “It’s raining cats and dogs,” with the cats symbolizing the rain and the dogs representing the wind and storm.
There have, however, been verified reports of animals falling to Earth during severe storms. So, while it doesn’t really rain cats and dogs, it may actually rain fish and frogs. No one really knows for sure how or why this rare meteorological phenomenon happens, but the most widely suggested hypothesis is that a strong winds, such as a tornado or waterspout, suck the creatures out of ponds and rivers and carry them to dry land.
Stories of animals raining from the sky, technically called “non-aqueous rain,” have been with us for thousands of years, including one account in the Biblical Book of Exodus, where a one of the plagues called down upon Egypt is a rain of frogs. As fantastic as these stories sound, there have actually been several more recent incidents of non-aqueous rain around the world.
In the last year alone, fish rained from the sky in two locations: Bhanwad, Jamnagar, India, on October 24, 2009, and Lajamanu, Northern Territory, Australia, on February 25 and 26, 2010. That same time period has seen several reports of frog and toad storms: The Ishikawa Prefecture in Japan experienced numerous occurrences throughout the month of June 2009, while Hungary, saw two storms between June 18 and 20, 2010. Other animals have also fallen from the sky in recent years, including worms over Jennings, Louisiana, on July 11, 2007, and spiders in Salta Province, Argentina on April 6, 2007.