This is a great example of weather and not climate. There are always one-off weather anomalies like snow one day in May or a 72 degree F day in December, but it's not good when these happen frequently.
Globally, the trends get warmer and warmer every year. Just because there was a warm December day 40 years ago doesn't really mean anything. What means something is these days keep happening more and more everywhere, and this has long term implications for everything. It won't be our extinction event but as other have said, we won't be living in the same world we are now.
I'm not from the area, so I'm unsure if there are severe micro-climates in or around Chicago. Maybe, even, you and your neighbor are acclimated to very cold weather conditions. It's irrelevant either way, as we would all be better served by not conflating weather with climate, which OP's post is also doing.
Because Chicago proper gets lake-effect cooling when the weather is warmer, and I was ~50 miles west of the lake, it was considerably warmer where I was.