And gladly would against the Fayr-day fit Themselves with such a Roofe, that can secure Their Wares from Dogs and Cats rain'd in ••owre, -pg17, Olar Iscanus, Henry Vaughn (1651)
It has been pouring-down rain in San Diego for the better part of four days. For any other part of the nation, other than the desert Southwest, this might be considered “stupid Californian whining”. But I know better having lived in much of the Eastern seaboard, the South, and the Pacific Northwest. I know rain, drizzle, hurricanes, snow, and floods. I’ve walked dogs most of my life, in every kind of weather. So a little rain is not something to think about. However, in April, in San Diego, the wet weather we have had off and on since late last year IS atypical. But Dexter and Comet will have none of my hesitation, regardless of the rivulets pouring off the roof at my front door, the soaking we will get stepping out, or torrent of water flowing south and west down my street.
Why am I thinking these animals care about my needs, or why am I wondering where the origin of “raining cats and dogs” came from? Obviously, as we were out sidestepping the flooding gutters and debris blocking the storm grates that push water over my boots, Dexter was hell-bent on a long, wet walk. Comet, more poo-driven, was searching for his spot, and then getting back to his “3-hots n a cot” life indoors. Probably he had suffered way too many days unprotected from the elements in his former street-dog life. Or so I imagined.
A wet dog is the lovingest.
Ogden Nash, poet, via https://www.poetrynook.com/poem/dog-2
Once we got home, dried off, and they were satisfied, I went back to the computer. In the boredom of quarantine, that philosophical burning about cats, dogs, and rain had to be answered. When the United States Library of Congress cannot categorically state certainty, but can provide four centuries of etymolog(ical) (-y, def. the study of the origin of words and the way in which their meanings have changed throughout history) references, I wonder. A Welsh poet, Henry Vaughan, might have been walking his dog in the rain, or making some veiled social commentary (Cromwell had overthrown the monarchy in 1651) and found inspiration. And many times since, have raining cats and raining dogs been curiously disparaged by poets, authors and others. And I found that I am not the only one thinking of this. Many, perhaps soggy, others, (dog-walkers?) have thought about this.
But nobody I fear notes the improbability of that etymological origin. No sensible housecat I have ever encounter associates himself with wet dogs, nor will, on purpose, be found in the rain.
It's a Dog's Life 