Season Shifting Pattern

In recent years it seems that the seasons (in Ontario anyway) are shifting dramatically! We have had warm weather in the teens on Christmas, no real snow until January, hot weather on the Thanksgiving weekend and very late spring with snow as late as May 30th. This seems odd to me. I remember snow in October, March thaw, and crisp Christmas weather. Even the birds are changing migratory habits by leaving later or staying behind for the winter. The great lakes have been surprisingly low for several years now. But I'm not convinced that the changes are totally to do with global warming and other catastrophe's that we are led to believe are changing the earth. There is potential for man and the earth to heal itself so why is the change happening?

I have some reason to believe that part of the explanation lies within the natural patterns that occur over time, though recorded facts of weather patterns are limited, so only geological surveys can discover some of the truth, along with recorded documentation in archives. Historical information is hard to find? Please comment to add some light to the matter.