I worked on a horse farm in Alaska one winter - often minus 60F or alittle lower in January-February. Most important, as always, is
head, hands and feet -
and layers. Old East german army "furflap" hat or wool knit hat with pull down face mask - and hat. Silk and or polypropylene knit glove liners and ski gloves or Dachstein wool mitts with cotton overmitts. Sorel Caribou felt lined boots with two to three pairs of socks. In between varied
down to (with little or no wind); cotton long johns under cotton slacks, T-shirt and long john top, sweatshirt and cheap quilted ski jacket (sometimes unzipped or
OFF when loading/unloading haybales, shovelling, cleaning corrals etc).
I have noticed a threshold at about minus 30 to 35 degrees, where with no wind the face must be covered or nosetip and ear frostbite begins. With a windchill factor the actual air temperature does not have to be very low for this to happen. Years of winter mountaineering, hunting and camping have taught me that a moderately low temperature with damp and wind are the most uncomfortable conditions to be in. Dry cold - well below 32 degrees fahrenheit - is better than "around 32"
and damp.
I am currently in Texas, so about the coldest I've experienced here is around 20F. My current choices are silk long johns - or cotton long johns can be worn over the silk. Intermediate layer of light wool pants or 100% cotton flannel and similar fabric shirt with soft wool sweater. I've also invested in some new surplus russian army hats similar to my old and well worn east german one - which although is still a good hat, starting to wear thin in the lining.
Outer layers; pure wool jacket and pants. I have a pair of wool aussie army pants and british army inuslated Goretex overpants if needed. I have a few jackets depending on conditions - cotton field jacket, wax cotton and wool/Harris tweed. If I do not need a pants belt to carry gear I use suspenders - more comfortable and do not restrict blood flow in the lower body.
Light silk sock liners, cotton nylon mix socks, then soft wool or Thorlo brand - may be two pairs if sitting in a stand is going to be the order of the day. I have recently aquired a new pair of insulated Irish Setter boots which I am looking forward to wearing; for severe cold though I would go with Sorel felt lined boots or similar from one of the other makers. Some surplus outer pac boots are another option. The only other thing I would add in sub-zero climes for hunting would be down coat and pants, both of which I still have from my winter climbing days - still servicable after thirty years(!).
Additional cheats are those little hot pocket handwarmers which can be stuffed in pockets, even in oversize boots. Very inportant to avoid sweating - you get damp, you get cold. Layered clothing allows you to regulate this.
Food and hydration; the right food - plenty of meat even if it is beef jerky. You need that fat burning to keep warm. Salmon is pretty good too as fish goes and if it can be kept available fresh/frozen. Water intake is critical - if you get dehydrated your whole system slows down and you are going to get cold. In extremely dry cold weather, even without exertion, you lose moisture very fast just through respiration.
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