My tailor is rich : another idiom

As it rains almost non-stop during 6 months of the year in Vancouver, I think this idiom will be very useful : "It's raining cats and dogs."

 
As you surely would have guessed on your own, it means "il pleut des cordes", but I do prefer the idea of cats and dogs falling than ropes, maybe just because I like cats...
Anyway, for the hypotheses regarding the origins of this idiom, it's here.