That's the golden rule of winter hiking for polar explorer Eric Larsen. "Your biggest problem isn't getting cold," he says. "It's actually getting too warm and sweaty, because once you stop moving, hypothermia can strike in less than five minutes on cold, windy days." So layering is key. If you start sweating, immediately shed layers or slow down. Here are the basics: >> Layer 1 (A) No matter how frigid the temperature, wear a light, long-sleeved baselayer next to your skin. Thinner layers wick sweat better and dry faster. Also, opt for shirts with thumbholes, which keep drafts from sneaking in between your sleeve and glove. >> Layer 2 (B) Next comes a thin midlayer—either wool, polyester, or a blend of the two. >> Layer 3 (C) A puffy, zippered jacket with a hood. This heat trap is your best friend in frigid temps. >> Layer 4 (D) A shell made of a waterproof/breathable fabric with taped seams. Size it big enough so it fits over everything else. And avoid white jackets and gear, which get lost in the snow.
Avoid stacking them around your neck and chin. Otherwise, you could have three to four zippers rubbing you wrong. Consider combining a crewneck baselayer with a zip-T insulating midlayer, then topping them with a neck gaiter.
Secure Your Hood
If the wind's whipping it, even with the cords cinched, put your goggle band over it.
If your goggles steam over, most likely it's because you're too hot. Unzip clothes, manage your body temperature, and keep anti-fog wipes in a handy pocket. Keeping your balaclava off of your nose also helps; just don't put your schnoz at risk for frostbite.
Wear Good-Fitting Gloves
If you have to remove them to tie a knot, your digits might freeze. A great dexterity test: Get dressed and undressed while wearing gloves. If you can't do it, keep shopping.
Zip Up Pockets
If you Don't "they can fill with spindrift when it's really blowing," says Brian Clark, a meteorologist who works at one of the planet's windiest spots, Mt. Washington.
They'll keep out snow and prevent your crampons from slicing your pants.
5 On-the-Move Tips
>> Keep food handy "Tear the corners off of several energy bar wrappers before heading out, then store the bars in warm pockets," says Larsen, "so you don't have to fumble with seals or remove gloves while on the move." For a quick energy boost, stow some hard candy in a pocket. >> Huddle up when talking to your partners It'll keep you warm and carry sound better. >> Work out sign language beforehand For example, holding poles out to the sides means "All OK." >> Carry an emergency bivy Ounce for ounce, they offer the most weather protection if a storm, whiteout, or injury traps you in the field for the night. >> Pack like a parachuter Load everything in reverse order. You won't need your bag or tent until day's end, so they go in first. Your puffy jacket, which you'll need at every rest stop, goes on top.