The essential guidelines I put down four years ago are still a good foundation, but with the snow beginning to pile up it’s a good time to mention some specifics which have proven constant from then to now.
The most useful tip for being outside in the cold is to HTFU (harden the fuck up). Hiking, skiing, hunting, boating and so forth out in the cold for more than a few hours can be both miserable and scary, and a great deal of equanimity can be won by accepting that this will be the case and by committing to a fine understanding of the distinction between uncomfortable and hazardous. The former is transient, though that isn’t particularly obvious in the moment, while the later can lead to frostbite, trenchfoot, and hypothermia (in no special order). No shortcuts here, time in the field is the only way to better know yourself.
Next on this semi-hierarchical list is to wear tall socks. Warming the blood as it heads to your feet puts you permanently ahead in the most consistently difficult game in winter. This is applicable whether you’re running thin liners inside a vapor-barrier sock for hiking or cycling, or thicker socks inside nordic ski boots. VBL systems are highly effective, and I use them extensively in temps below 20F, but they are not as universal as tall socks. Pay extra for ones that don’t sag (I like Smartwool, marginal durability notwithstanding), and when it’s below freezing don’t go out without them.
For winter insulation, and indeed layers of all types, favor breathability over absolute warmth. In the end insulating value is not about lab numbers, it is about how a system addresses the full range of way you get cold under field conditions. Convective heat loss from perspiration is almost always the most problematic of these, making it more consistently effective to wear a few more and/or thicker pieces which are more breathable, rather than address the same conditions with the lightest and fewest pieces of clothing which are more protective but less breathable. Using Patagonia’s Capilene 4, or the many imitators, against the skin is a prime example. Cap 4 is warmer, statically, than Cap 2 even though they’re roughly (120 g/m) the same fabric weight, but in the cold Cap 4 moves moisture so well it is the cold weather baselayer. Polartec Alpha is another example. On paper it doesn’t pencil out well, and is more expensive than fleece plus windshell, but aside from summer I’ve rarely left my Strata hoody home, and when I do I usually wish I hadn’t. Since I cut the sleeves off a few months ago it’s been even more in demand.
Appropriate layers of head insulation is another key to cold weather success. The old tales that you loose some huge percentage of body heat via your head were hyperbolic, but it is surely true that head insulation give you more warmth per are covered than any other. More significantly, unlike torso and leg insulation hats and hoods are quickly added and subtracted, making variable head insulation an easy way to thermoregulate. I strive to assemble a system which is breathable, and where all the hats and hoods I have can be used at the same time, without engendering the rubber band effect. In the above photo I’ve got a Kuiu Tiburon ball cap (for keeping snow out of my glasses), Coal beanie (stretches to fit over other stuff), buff (around my neck), and the hood from my Strata. The hood of the Haglofs Ozo rain coat (worn for paddling only) or the BD Alpine Start (for hiking) fit over all of that comfortably.
Lastly, protect your crotch. I can’t ever recall thinking oh darn my knees are cold, but I’ve suffered with a cold butt and (even worse) cold crotch on numerous occasions. On top of those visceral concerns, insulating the big arteries which run through your upper thighs has a preemptive effect similar to wearing tall socks. Dearly departed Cloudveil made some heavier Powerstretch boxers for a few years, and while I don’t recall what possessed me to buy them, they’ve been an outstanding winter piece for many years. They’re not on the level of wind briefs, but they’re also more widely applicable. Buying a pair of powerstretch tights and cutting them off would not be a bad way to go, at all.
So get out there. Being cold can kill you, but not as easily as most think. And you’ll definitely learn something.