I have an unusually low body temperature to begin with, (often under 35ºC as opposed to 37ºC...
indoors) so I am particularly susceptible to cold weather. My hands get so cold that I can hardly manage to hold my equipment, and my workflow becomes a series of jerky, desperate motions. It is difficult to force myself to slow myself down into a normal working rhythm. Once my body core gets cold, my whole body starts to shudder, and there is nothing for me to do but pack up and head inside. I did a winter shoot with Marc A (filmsprocket) last year, and was frozen to the core before he even began to feel the cold.
I tend to leave my feature-laden cameras in the bag and use simpler equipment... An aperture, a shutter and a film crank are about the most I can handle in the cold and dark. (oh, ya... for some strange reason, I tend to to a lot of night photography in the winter) Like tripods, camera bodies also suck a lot of heat from your hands, and complex adjustments require dexterous fingers on the controls. I have tried a number of systems, and tend to stick to thin wool gloves for working and warm loose mittens for warming.
As much as I admire Michael Kenna's wonderful composition and printing, I am in
awe of his ability to work
bare-handed in deep snow with nary a flinch. I think if I did that I'd be looking through the snow for my fingers.
As others said earlier in this ancient thread, winter is a good time for studio work. I can play with a still-life table for days before I get bored and have to tear it down and start again. One benefit of this is that I can work at consistent light levels for a large series of shots and concentrate on composition and camera movements, etc. I can also leave my setup intact for days on end, tweaking my workflow in a way not possible in the cold. (not to mention that I don't have to keep my kit dry and search for lost cable releases in the snow)
Cheers, and stay warm.