My Dad also taught me about the wooley caterpillars predicting the severity of the up-coming Winter; the heavier and darker their coat (not to mention, the EARLIER they don it), the more severe the Winter will be. Another one I remember is the ring around the moon, predicting a rainfall soon; if you see a ring around the moon one evening, then within 2 days it should rain. I've always found that one to be true. Interesting.
Cat, we also use the forsythia blooms as a barometer for things here - when you see it FIRST start blooming, that's when it's time to put the corn gluten down on the lawn as a weed-preventer.