The much more probable source of 'raining cats and dogs' is the prosaic fact that, in the filthy streets of 17th/18th century England, heavy rain would occasionally carry along dead animals and other debris. The animals didn't fall from the sky, but the sight of dead cats and dogs floating by in storms could well have caused the coining of this colourful phrase. Jonathan Swift described such an event in his satirical poem 'A Description of a City Shower', first published in the 1710 collection of the Tatler magazine. The poem was a denunciation of contemporary London society and its meaning has been much debated. While the poem is metaphorical and doesn't describe a specific flood, it seems that, in describing water-borne animal corpses, Swift was referring to an occurrence that his readers would have been well familiar with: