I was similarly caught out just before New Year's. I left the village at 2:00 PM and headed north towards Germany on dry roads with no wind and scattered clouds.
I reached Koblenz on the Rhein when a snow squall came down from the Black Forest. I was in Zurzach and 30 km from home before I realized that I was in trouble. The snowflakes were wet and the size of 2 CHF coins. The wind was howling by this time, visibility was 10 metres and I couldn't feel my hands. Was I shifting or braking? ...couldn't tell.
I had ridden this route 150 times, and this was supposed to be a cakewalk. No cellphone, no wallet, no brain. Just a quick spin before the next holiday party.
I knew that if I kept the hammer down, I would generate the heat that I needed. I arrived home with no feeling in my hands, body shivering and my thighs lobster-red.
Another 5km and I would have been a pop-cycle (get it?)
Never had a winter-survival tale to tell while I lived in Canada, but now that I live in Switzerland, I almost perish!
Guess I've lost too much blubber.