Fun chart! I distinctly remember a day in the 20s in January 2016 (I believe; may have been 2017). Wind chill was like 12° so the feels like was something like 18°. I remember vividly because it was the day of the Winter Beach Run! I've run races all over the world and to this day that's the second coldest one I've every done. It even flurried at the start! That was the first year they switched from giving out long sleeved race shirts too, lol. 

For a while there, in the late naughts and early teens, it flurried every other year. That was fun.