Congratulations,
Congratulations, BarefootGentile! That is quite an accomplishment.
This was my first winter as a barefoot runner, and I had the opposite experience. I ran barefoot throughout the fall as temperatures fell, and thought I was getting used to it. We had snow just before Thanksgiving and I ran in it (some of it was slushy on the ground). It was fun, but I paid the price later with very painful hotspots. I continued to run in the relative cold (almost always above freezing), but my tolerance decreased. I continued to get hotspots (even when I didn't get them in warmer weather -- the old "numb foot is a dumb foot" phenomenon). In mid January, I went running on a dry 35-38 F day, and got the worst blood blisters (my first from barefoot running), the kind that under several layers of skin. After that, I decided to run on the treadmill whenever the temperature was less than 50F. Next winter I will try Ken Bob's advice to do short runs outside in the cold (maybe just 1/4 to 1 mile) alternating with running on the treadmill during the same "run". Although I love running outside year round, I like running too much to risk injury by running any significant amount in minimal shoes (already happened 3 times in my experience).
TJ, I think your point about individuals varying quite a bit in their cold tolerance is right on. In my case, I think my extremities tend to be naturally cold (cold hands and barefeet, even when otherwise warmly dressed indoors, but I don't have Raynaud's or anything like that). Some of us just might not be cut out to be cold weather barefoot runners.
Another topic that has been discussed here and elsewhere quite a bit is hotspots/blisters and running in wet conditions. My hypothesis (at least as it applies to me) is that it's not so much the moisture itself or softening of the skin it might cause, but the cold/numbing effect it can have, even when the temperature is not very cold (say, in the 50s [F] or possibly even warmer).
