Up until January of this year, I was most certainly a year rounder, and have ridden in single digit (F) temps. I had multiple layers on, of course.
When I hit that patch of black ice under a freeway overpass and lost it, however, that changed my attitude. Since then, freezing has been my threshold, as you never know when a little water dripping from the bridge above will turn into a bad day.
Live and learn, IF you live of course.