rain cats and dogs

Verb

rain cats and dogs (third-person singular simple present rains cats and dogs, present participle raining cats and dogs, simple past and past participle rained cats and dogs)

1. (idiomatic, impersonal) To rain very heavily.
   • ["]Those weather-gaws aren't out for nothing. It'll rain cats and dogs to-morrow." Marigold wondered what weather-gaws were—and then forgot in thinking how interesting it would be in it really rained cats and dogs. Little silk-eared kittens everywhere by the basketful—loads of darling pudgy puppies.1929, L[ucy] M[aud] Montgomery, “Marigold Entertains”, in Magic for Marigold, Toronto, Ont.: McClelland and Stewart, →OCLC, section 4, page 190

   Synonyms:

   bucket, bucket down, chuck it down, come down cats and dogs, rain buckets, rain pitchforks, pelt, piss down, piss it down, pour