I can try to look up the data however It's a little more difficult in the North country due to less climate stations. I would think Sault Saint Marie is probably the best option to look up? One thing that's pretty certain, it doesn't matter where you are looking, the 1970s were the coldest winters on record just as the 1930s & 1950s were some of the, if not the, warmest. So any Temp graph would have a similar downward curve if you did 1920 to 1970, upward curve you did 1970 to 2020, or a more subdued upward curve if you did 1920-2020. Snow and snow depth would be the interesting one, and I would think that either Alpena or the Soo would be the only places that had consistent records.
interesting enough, the 2010s had the most 6"+ snowdepth days on record at Detroit, thanks in large part to 2013-14 & 2014-15...2nd place was the 1970s. The 1940s had the least.