The wet weather produced them? What, do they grow from raindrops?

Hm... *suddenly realising crashing ignorance of snail reproductive habits.* Hmm... A quick Google on another tab reveals many interesting things. "Hermaphrodite snails can reproduce mutually." No, perhaps best not to ask...

I suspect that the Snail Commandant has told your local paper the exact numbers. Something along the lines of "Tremble, Earthlings, for we come in numbers 36 trillion strong to get crunched under your feet take over your puny planet."