> "Blinding flash" actually is easier, especially in a post-Alamagordo
> universe. I have no idea where "cats & dogs" came from (I know, their
> mothers). There is a perhaps "rural legend" that in the middle ages the
> household beasts might congregate on the thatch roofing of the houses.
> When the rain because intense enough, you had a Jersey Shore effect and
> the roof fell in. Cats and dogs fell in with them. There are other
> explanations, meaning that none of them are worth very much. A poet's
> reflections are worth as much if not more than an etymologist's,
> entomyolygist's, veterinarian's, or member of the cast of Six Feet Under.
>

Thanks for yr comments, Ken, Randolph, Doug B. On cats and dogs as
meteorological events, one can happily say that nobody knows the true origin
of the phrase. Wordorigins.org has a succint summary, it's rather pleasing
to realise that there is so much in the language that cannot be
butterfly-pinned by the etym-entoms.

Like a hint of a secret palyground for poets.

Here's the wordorigins bit reproduced:

"Rain Cats and Dogs
Like many other phrases contained in these pages, the origin of this phrase
is unknown. Its first recorded use of the phrase in its modern, familiar
form is by Jonathan Swift in Polite Conversation, written circa 1708 and
published thirty years later:

  I know Sir John will go, though he was sure it would rain cats and dogs.
This work of Swift's is a satire on the use of clichés, so the phrase was
probably in use for a considerable period before this. There are a few
variant uses recorded as early as the 1650s. Henry Vaughn's Olor Iscanus of
1651 goes:
  The Pedlars of our age have business yet,
  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 showre
A year later Richard Brome writes in his The City Witt:
  It shall raine...Dogs and Polecats
And the Oxford English Dictionary records various proverbs and quotations
that make use of the metaphor of a cat and dog fight from 1579 onwards.
Suggestions for its origin include:

  a.. The archaic French catdoupe, meaning waterfall or cataract.
  b.. A hard rain in London would drown many stray cats and dogs, making it
seem as if they had fallen from the sky.
  c.. In Norse mythology, cats had an influence on the weather, and Odin,
the sky god, was attended to by wolves.
All of these are unlikely given the early metaphorical uses of cat and dog
to signify something noisy and violent. The most likely explanation is the
simplest. The noise and violence of a storm is the metaphorical equivalent
of a cat and dog fight.

There is an internet myth circulating that says the phrase is from the fact
that dogs and cats (and other animals) would live in thatched roofs of
medieval homes. Heavy rain would drive the cats and dogs out of their
rooftop beds, hence the phrase. There is no evidence to support this
contention. More information on this myth can be found in my book, Word
Myths: Debunking Linguistic Urban Legends.

(Source: Oxford English Dictionary)"



Best

Dave