OK, I grew up in Upper Michigan. When I was a kid, Winter routinely lasted until mid-to-late-April, and we often had snowfall into early May. Spring wasn't considered to have started until April at the earliest. So the Groundhog Day tradition just confused the heck out of me. "Six more weeks of Winter" would have meant it ending in mid-March, which was unthinkably early to me. And yet they talked about "Spring coming early" as the other possibility. To me, both outcomes meant Spring coming early!
My Grandma's rule of thumb was: seeing the first robin meant Spring had started. That seemed a lot more reliable to me, since robins didn't usually show up until late April, back then.