Bare feet can attract a fair bit of attention or wonderment even when it is warm out, but during the wintertime, folks really don’t know what to make of it.
I suspect one reason is that so many people’s feet are regularly cold. However, regular barefooters don’t seem to suffer from the cold feet that so many shod people do.
There’s no real reason feet should be colder than, say, your hands. Genetically, they are very similar appendages. If you don’t need gloves, you probably don’t need shoes, either. True, when barefoot, the soles of your feet are touching the ground, but there are a couple of things that ameliorate that. First, in the fall and the early winter the ground is often warmer than the air temperature. Later in the winter and into early spring the ground often is colder than the air, but regular barefooters usually have a fairly thick buildup of padding on their soles, and that provides insulation. Second, if there is a wind of some sort, the wind is usually much lower near the ground (where your feet are), so your feet are not subjected to the wind chill that your hands are.
There is another reason that a bare foot can stay warm: it can move and gets good blood flow. Lacing up a shoe does do a good job of keeping the shoe on, but that tightness can restrict the flow of warm blood to the foot (actually, since veins are on the outside, not arteries, it’s probably blood flow out of the foot that is restricted, but if blood has trouble getting out, new blood has trouble getting in). Additionally, when your foot is bare all of its parts can work together to massage warm blood in and out. The movement and use of its 26 bones and over 100 muscles, tendons, and ligaments is helping to pump blood through all parts of the foot. When your foot is bound inside of a shoe, practically none of those parts are moving relative to each other—they are held immobile by the shoe, and so the blood flow is reduced. No wonder shod feet get cold!
It is also the case that the body adapts. If, as winter approaches, you keep going barefoot, your feet will acclimate and will get better and better at tolerating (and even relishing) colder temperatures. Various barefooters also report that, year-to-year, cold tolerance increases. It seems it can take 3-5 years of winters before the feet finally realize what they have to do to remain completely comfortable in temperatures that make the shod shudder at just the thought of going barefoot.
In our modern society, most folks aren’t outside for all that long anyways. Most barefooting in the winter is probably done between our cars and a store. For that short distance, even in quite cold conditions, the feet can take it just fine. Again, if you don’t need to put on gloves to run into a store, you probably don’t need shoes, either. Nothing will happen to them over that short distance (except, maybe, a bit of invigoration).
After getting acclimated, a barefooter can still feel the cold, it’s just that their feet aren’t cold. It’s like eating ice cream. The ice cream feels cold when you eat it, but it doesn’t make you cold, and it feels great going down (unless you do too much, too quickly; then, brain freeze). Going barefoot in the cold is like that. It’s mostly a great, different sensation, as long as it is not overdone, just like ice cream.
Let me end with a word of warning. Subfreezing cold can be dangerous. In the winter, know what you are doing, know your limits, and carry emergency footwear in your car, along with a spare blanket, snow brush, and roadside flares.