"It rained much yesterday" was regarded as wrong....Granted, "a lot" does sound better in English, but I don't think "much" is completely wrong...
Even if much is not incorrect grammar, which I believe it is, no one would use that phrase.
Although I admit it probably doesn't seem very logical, you'd normally only use "much" if the sentence were in the negative, ie "it didn't rain much yesterday".
I am anative english speaker and saying it tsined much yesterday is 100% correct!