Winter Boots
If your hiking takes you out when the temperatures are much below freezing, you'll want to consider two other categories of footwear: pac boots and what I'll call winter hiking boots.
Boot guru Steve Komito's shop once contained a sign that read, "Double boots are cheap – only $30 per toe." The sign, which was promoting ultra-warm boots consisting of an outer shell and a heavily insulated inner boot, was aimed at winter mountaineers and Himalayan aspirants. Its message, however, is equally applicable to anyone who goes out in frigid weather: insulated, waterproof footwear is worth the price – especially considering that the price of inadequate winter footgear may be frostbite. After all, he who dies with the most toes wins.
Pac boots have an all-leather or leather and fabric upper stitched to a molded rubber bottom. A removable liner, usually made of wool or polypropylene felt, provides insulation. Wool liners cost less; polypro liners dry faster. For equivalent thickness, the warmth is about the same. Pac boots are warmer than winter hiking boots – sometimes too warm – and totally waterproof up to the top of the molded rubber. They're water-resistant above that. Pac boots are instantly comfortable, requiring no break-in time, but the fit is usually rather amorphous because the insulation compresses under your foot and the boots are normally available only in full sizes. When fitting a pair, make sure the top edge of the molded rubber doesn't jab you under the ankle bone while traversing a slope.
Pac boots are perfect for aurora watching and other inactive pursuits. For strenuous hiking or snowshoeing in rough terrain where you want a snugger fit and better ankle support, look for a pair of insulated, waterproof winter hiking boots. They'll lighten your wallet more than pac boots, but also lighten the load on your feet.
Many of these boots are marketed as hunting boots because they're targeted to the hook-and-bullet crowd, but don't let the name put you off. Hunters spend a lot of time walking off-trail in cold, snowy or marshy terrain, and they need warm, waterproof footwear more than most backpackers. Cold-weather hiking boots have all-leather or fabric and leather uppers that are stitched, cemented or attached via injection molding to a stout lugged sole. All three construction techniques, including injection molding, which has been much improved in recent years, produce a durable boot. All-leather uppers typically cost more, weigh more and last longer. The insulation, which is stitched permanently into the boot lining, is usually Thinsulate, a microfiber batting that resists compression and provides a lot of warmth with minimum thickness. Some manufacturers use various closed-cell foams as insulation, which don't provide quite as much warmth as Thinsulate for equivalent thickness. As with summer hiking boots, the best insulated winter hiking boots back up their leather with a sewn-in Gore-Tex bootie.