Funny thing about the fog - it's actually nice and warm (for something that is supposed to be cold and damp). I've been quite comfortable riding into work before dawn when the fog has been around as it's taken the edge off the morning cold.
Just when you get used to something nice, it ups and disappears on you. This morning was crystal clear - and crystal cold. Within a few minutes of hitting the road, I thought my arms were going to freeze off. I was cursing myself for not adding a thermal shirt under my jersey.
That quickly passed - by the time I got to work, I had sweat pouring down my face and dripping down my arms. If I'd added the third layer, I would have died from heat exhaustion.
I need to remember that sort of thing next time I find myself going soft at 0600.