The mystery of raining creatures

Non-aqueous Rain

Rare and yet real, cases exist of rains of animals instead of water. This has occurred occasionally throughout history, from the Biblical times up to recent history.

In English, we often say, “it’s raining cats and dogs” when its pouring down. There are records of its use dating back to the 17th century.Whether or not it arose from non-aqueous rain is still unknown. Its origin has been linked to thatched peasant homes were animals could crawl into the thatch and find shelter from the elements but would then fall out during heavy rain. 

http://patternizer.wordpress.com/2011/01/05/the-mystery-of-raining-creatures/