I turned to our print thesauri first, but wasn't able to find anything. Then, I found an online thesaurus that listed some antonyms for words similar to drought (absence, famine, thirst, etc...) These were some of my favorite suggestions: abundance, surplus, plenty, monsoon, feast. I liked all of these as general antonyms for drought, but I was searching for something a bit more "meteorological" in nature. (I assumed our Meebo friend was, too.)
I checked out a few of our print weather encyclopedias, but again, without an actual word to look up, I was stuck. Turning back to the internet, I "did the Google," as my dad likes to say, and stumbled on this website. After bandying about the words monsoon, deluge, and flood, pluvial seemed to stick out as the most apt opposite for drought. Here's what the OED had to say:
This quotation that was used to illustrate the word was the cincher:
1970 W. BRAY & D. TRUMP Dict. Archaeol. 184/1 Prolonged periods of high rainfall are called pluvials, and are marked by changes in lake levels and in flora and fauna.
Oh, dear. It's started raining again.
"pluvial." OED Online. Dec. 2008. Oxford University Press. 30 October 2009 http://dictionary.oed.com/cgi/entry/50182124.