The Cold-Weather Gear That Kept Me Warm amid the Subzero Temperatures of Denali
The best gear for staying comfortable and climbing on North America’s tallest mountain
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You have to be a little bit of a masochist to spend much time on Denali. In the early season (beginning of May), temperatures regularly plunge to 20 below on the upper mountain. You have to be willing to suffer a tad in that environment, but that suffering can get out of hand quickly without really warm gear.
When my team and I flew onto the Ruth Glacier on May 8 last year, we went prepared for serious cold. We didn’t reach the summit, but we did get a good taste of all the weather Denali had to offer. After two winters in Colorado testing every item, seeking out the best approximations of Alaska (mainly the lowest temps, strongest winds, and most exposed campsites the Rockies have to offer) to double-check that everything performed, I was confident in the gear I took up the mountain. Here’s what kept me warm and comfortable while climbing in Denali’s 40-mph winds and subzero temps.
Scarpa Phantom 6000 Boots ($949)
Choosing what boots to pack for a trip like Denali is tricky. You need a single pair that breathes well enough on the lower glacier, where daytime temps are in the fifties, and can still keep you warm on summit day when it can be 70 degrees colder or worse. I also wanted something with a toe and outsole precise enough for more-technical climbing. A good compromise between limitless warmth (and bulk) and a bit of precision was a 6,000-meter boot with 40 Below K2 Superlight Overboots. The Phantoms use PrimaLoft Micropile and EVA to insulate enough for 90 percent of the mountain, but on the coldest days I could slip the neoprene overboots over the top for extra insulation. My feet don’t typically have major issues with cold, though. For my climbing partner who suffers from chilly extremities, La Sportiva Olympus Mons, with even more insulation and integrated overboots, were a one-stop shop.
Feathered Friends Down Booties ($119)
While the Phantom 6000s do have internal liners, they tended to get wet over the course of the day, especially on the lower mountain, where warmer temps made my feet sweat and mushy snow dampened them on the outside. So I got in the habit of slipping out of them as soon as we arrived at camp and finished digging, dropping the shells in the vestibule of my tent, slipping the sweaty liners into my sleeping bag, and sliding on my Down Booties. Cozy 800-fill down felt amazing after a long day in constricting boots, and the removable weather-resistant shell made it easy to step outside to pee or hang in the cook tent without getting them wet and ruining my foot warmth.
The North Face Summit Futurelight Belay Mittens ($165)
If there’s any item to bring in excess onto Denali, it’s handwear. I brought three pairs of gloves, plus these beefy down and PrimaLoft mitts, so I could fine-tune my selection for the conditions of the moment and get a set wet without being totally out of luck. Unlike my feet, my fingers get cold quickly. And thanks to an internally split finger compartment, these mittens allowed just enough hand function if I needed to ditch my lighter gloves for something warmer midclimb. This is where gear confidence is key in the Alaska Range. If you know you can reach into your pack and have warm hands whenever you need them, you’ll feel exponentially better about your preparedness.
Smartwool Mountaineering Extra Heavy Crew Socks ($25)
Socks, like gloves, are most effective in numbers. Expect them to get wet and need continuous drying, usually in your sleeping bag near your chest at night. I needed only three pairs of these super-heavy wool socks for a two-week trip: a couple pairs in daily rotation that held their shape and didn’t get smelly thanks to their sturdy woven arch brace and merino’s odor-resistant properties, plus a pair sealed in a Ziploc bag specifically for summit day. The extra-heavy weight was necessary for the colder days (and I sized my boots specifically to fit them), but the breathable, wicking merino kept them from becoming totally useless on warmer days. Setting aside a set that had kept me warm for soggy hikes and windy climbs and unwrapping those summit socks once we made the decision to turn around was definitely bittersweet.
Therm-a-Rest Polar Ranger -20 Sleeping Bag ($750 and up)
Even in a place where the sun never fully sets during the summer, conditions change a lot at night. When the sun is just skimming across the horizon and ducking behind other peaks, all the heat that the sun baked into the snow and rocks during the day evaporates—fast. A sleeping bag like the Polar Ranger (designed with the help of Polar explorer Eric Larsen), with 800-fill down insulation (which doesn’t wet out with a little moisture), is crucial for a good night’s sleep in extreme cold and wet. The hood’s magnetic openings made it easy to tuck my face away from chilly air, and on stormy evenings when I was killing time in bed, I could slide my hands out of the arm holes to read a book without unzipping the bag.
Patagonia Grade VII Down Parka ($899)
I brought only three different upper-body layers to Alaska: a lightweight active insulator, a midweight synthetic puffy, and a massive parka. The versatility that would come from adding an additional layer to this kit wasn’t worth the space it’d take up in my pack. But that parka was a doozy. The Grade VII’s massive baffles kept the 800-fill down lofted and maximally insulating, and the extra coverage from the long hem and big helmet-compatible hood provided nearly instantaneous warmth during my trip. The snow skirt, elastic cuffs, and elasticized side panels ensured a snug, warmth-retaining fit, but there was still room for my other layers underneath when necessary.
Therm-a-Rest NeoAir XTherm Sleeping Pad ($230 and up) and NEMO Switchback Foam Pad ($55)
Two sleeping pads are better than one, especially on snow or ice. Your sleeping bag isn’t something to skimp on, and neither are your pads—without sufficiently insulating ones, your pricey down bag won’t be as effective at retaining heat. Most climbers you see on Denali use a super-insulating inflatable pad with a foam pad underneath. I went with the XTherm, which has a crazy-high 6.9 R-value (the rating for how resistant to heat flow, or insulating, something is; the higher the number, the more resistant to heat transfer) and the Switchback, which adds 2, bringing my cumulative R-value up to almost 9. Both pads pack down small (I carried the foam pad strapped to the side of my backpack, and the XTherm is about the size of a disposable water bottle). And, conveniently, the XTherm comes with an inflating bag that makes blowing it up a whole lot easier in the thin air.
Mountain Hardwear Compressor Pants ($175)
Puffy pants are one of those pieces of gear you never knew you needed until you tried them. On chilly overnights in Colorado’s San Juan Mountains, they were an epiphany. Just slap them on over your ski bibs or climbing pants (no need to take your boots off—they have full-length side zips) for instant and appreciable warmth. In Alaska, they were perfect around camp at night or sitting in our group kitchen tent. They’re synthetic (using Mountain Hardwear’s proprietary Thermal.Q Elite insulation), so not as packable as down but more durable than down for sitting or kneeling. The 20-denier nylon ripstop fabric on the knees and seat held up to wear and tear.
40 Below Bottle Boot ($40) and Insulated Food Bag ($20)
Because of the technical route we chose for our trip, it was easier and more time-efficient to pack cook-in-the-bag dehydrated meals rather than bulky ingredients (not to mention the minimal cooking space higher on the mountain). With a stove like the MSR Reactor, which has a wind-blocking design and efficiently sips fuel, getting the water hot was no problem—but once we added it to our food, we had to find a way to keep it warm while the food rehydrated (which takes extra time at altitude). The 40 Below’s Insulated Food Bag is a neoprene pouch that helps the cook-in bags, which are insulated with much milder climates and shorter cooking times in mind, retain heat while your chili mac rehydrates. A loop on top lets you hang the whole thing in the tent and keep it from tipping or getting crushed. The brand’s Bottle Boot is also a staple on Denali to prevent water from freezing. You’ll still want to keep fluids in your backpack on really cold days, but the neoprene sleeve keeps your water from turning to a block of ice.