Already all sensation had gone out of his feet. So long as he walked four miles an hour, he pumped that blood, willy-nilly, to the surface; but now it ebbed away and sank down into the recesses of his body. The extremities were the first to feel its absence. His wet feet froze the faster. - Jack London, To Build a Fire
Your feet are farther from your heart than any other part of your body. So when it's cold out, it's very hard for your body to keep them comfortably warm.
Author Jack London understood two of the best ways to have warm feet in the winter: keep moving and keep your feet dry. On a frigid February day, your feet may feel plenty warm while you're walking but become incredibly cold if you must remain idle, even though you're still in the same pair of boots. Also, if your feet ever get wet, they'll feel much colder and will lose heat faster.
These principles highlight the important role activity plays in your choice of boot. If your outdoor activities normally involve sitting stationary or trudging in wet snow, such as ice fishing or snow shoeing, you need bulky, heavily insulated pac boots. If you plan to be walking or moving a lot (i.e., working on a job site) and will avoid deep snow, fit is more important than heavy insulation, and you'll need a snug boot that prevents your feet from sliding around. Either way, you'll want boots that are very water-resistant. Many people require a pair of heavily insulated boots and a pair of lightweight winter boots to accommodate all their winter activities.
All recreational winter boots are sturdier and more insulated than boots designed for fashion, and any true snow boots are also waterproof or highly water-resistant. Also, while virtually all winter boots are made to spend time in wet, snowy winter conditions, some are specifically designed for more active outdoor enthusiasts.
"P-A-C" spells warmth. Well, not really - but it should! The dictionary defines pac as "a moccasin or soft shoe designed to be worn inside a boot." So pac boots are essentially any winter boots with a soft inner "shoe" - in the form of a thick, insulative, removable liner. Pac boots have been the warmest winter boots out there for decades, but they've come a long way from the original crude, oversized boots that were insulated well but hard to maneuver in.
Now many pac boots are designed to keep feet comfortable over many miles. These boots are great for snowshoeing or shoveling the driveway - and they are still the best choice for motionless activities like ice fishing, or any activity involving trudging around in deep snow. If you have naturally cold feet, you'll really appreciate the warmth of this type of boot. Plus, their liners can be removed to dry quickly, so you'll never have to put cold feet back into wet boots.
Generally speaking, cold-weather hunting boots are more rugged, lighter and less insulated than pac boots. These boots often offer Gore-Tex® waterproof protection in case you must walk through shallow water. Insulation, fit, weight and traction are all equally important in a winter hunting boot. These boots may be designed for hiking over rugged terrain if they have Vibram® hiking-style outsoles, and often are insulated with lightweight Thinsulate® insulation instead of having a thick, removable felt liner.
Quick Tip: For motionless hunting in very cold weather, consider switching to a pac boot.
You don't have to sacrifice style for function. Many fashionable winter boots have style features that also serve to keep you warm, like faux fur cuffs, shearling insulation or a wide slip-on design that creates extra airspace for warmth. Remember that your boots need to get you safely and comfortably through a ski town, so avoid overly high heels, a lower ankle height and smooth, non-gripping outsoles.
Winter work boots are similar to winter hunting boots, but are almost always constructed of thick leather for durability, and may come with a steel toe. Buy the steel-toed version only if it's really necessary, as this feature can make your toes uncomfortably cold. Expect a lugged, heavy-duty outsole and a shock-absorbing midsole.
Snow boot uppers are usually made from leather or heavy-duty nylon, both of which are resistant to abrasion, punctures and wind. Snow boot uppers also generally feature sealed or "taped" seams to block out melting snow.
The upper on any winter boot must extend at least above the hem of your pants, but will need to reach well above your ankles for extra warmth and protection from deeper snow and colder conditions. The upper must be at least water-resistant, but will ideally be fully waterproof for extended use in wet, melting snow or mud-and-slush conditions.
Many heavy pac boots have a fully waterproof, injection-molded rubber shell (the "cupsole") welded to the upper to form the lower part of the boot. This shell's main function is to keep moisture from seeping in. Boots designed for lots of hiking, on the other hand, have a tighter fit around your ankle to reduce sliding or twisted ankles - which may mean sacrificing this rubber shell.
Rubber bottoms are great for blocking moisture out - but they also trap moisture in. The best way to deal with this is to wear moisture-wicking sock linings against your feet, with a pair of thicker wool or synthetic socks over the liners. Never wear cotton socks with winter boots!
The removable felt liners found in pac boots are usually made of polypropylene, wool, acrylic, Zylex® or a blend of these materials. They offer exceptional warmth but a loose fit. These liners sometimes come in a stated thickness, around 8 or 9 mm.
Thinsulate® insulation gives non-bulky, lightweight warmth that's best for active winter recreation. Here are a few rough guidelines to follow so you pick the best amount of Thinsulate® insulation for your needs:
Finally, fashion boots often use natural shearling for insulation. The warmth comes from the thick underwool of sheepskin, which has been turned inside-out so it cradles your foot. This form of insulation is surprisingly effective, but usually these boots are poor at repelling water and are best for snow-covered sidewalks or nights on the town.
Many pac/ winter boot manufacturers provide temperature ratings for their boots, such as "Rated to -50° F." These ratings are determined based on varying scientific measures, and will not apply to everyone the same way. Use these ratings as a general guide to figuring out which boots are the warmest, but don't expect the boots to perform to that exact temperature rating. Your health, activity levels, clothing, perspiration, exposure time and other factors can all alter the effective temperature rating.
Many pac boots have a fleece, wool or acrylic collar or "cuff" appearing above the upper, which is actually attached to the boot's inner liner. Sometimes called a "gaiter," it's designed to fit snug against your leg to block out snow. Some boots go one step further and offer a pull-up gaiter with a drawstring closure at the top to keep snow out. Regardless of whether your boots have a cuff, gaiter or neither, always pull your pant legs down over your boots to keep snow out in the backcountry.
You'll want a full lacing system - not just several sets of D-rings - for most active winter sports or outdoor work. Full lacing will provide a tighter fit and prevent foot or sock slippage, but is not offered on many pac boots.
So should you sacrifice the warmth of a crudely laced pac boot for the better fit found with full lacing? Pick your boot by deciding if fit is more important (go with full lacing) or if extra warmth and deep-snow protection is required (a good idea to forego full lacing and grab a pair of pac boots).
There are multiple types of lacing systems; here are the main ones:
The bottom of your winter boots, or "outsole", should always be made of waterproof, durable rubber or a similar material. This 100% waterproof barrier will extend upward if the boot has a rubber "cupsole"-style bottom. Keep in mind that for activities that involve a lot of walking, great traction in the outsole may be more important than a fully waterproof cupsole that extends over your foot and ankle. Virtually all winter boots should offer decent traction on the snow, though.
Select your winter boots based on the activities you have in mind. Heavy pac boots with thick insulation are best for people with naturally cold feet, those who trudge often in deep snow, or those who spend a lot of time motionless in the cold. Lightly insulated boots with a more snug fit and full lacing are best for people whose winter activities involve lots of walking or outdoor work.
Chances are, one type of boot is not going to cover you for every winter activity, and you're eventually going to want a few different pairs to effectively cover all your needs. If you can only afford one pair now, just get the style you'll use more first, and buy another pair later.