A short 10 mile loop today in 34 degree cloudy weather - mostly because my wife said I'd be crazy to ride so I wanted to prove her right. My normal "rules" for riding are: dry roads, over 40 degrees, and (wind < 10 OR sunny), so by my normal rules it failed. You guys in cold climates will probably laugh, but I decided I have the right to be warm as I get older.
Partly I wanted to check if my clothes were up to the task. Shoes, tights, jacket and skull cap were fine. The only disappointment was my Pearl Izumi Cyclone gloves; even with a liner, my fingers were freezing and getting numb. I think I need mittens or thick gloves below 40.
Luckily my jacket had front pockets, so I alternated riding one-handed on each side. I discovered that doing so also gives a better workout of the core muscles than 2-handed riding, which made me happy.