How to build an outdoor layering system for backcountry hiking & extreme alpine conditions

Lightweight wool base layer

This is your everyday base— light, soft, and breathable, made from 100% Merino wool. It regulates your body temperature, wicks sweat, and doesn’t hold odour, which makes it perfect for everything from midday hiking to alpine layering to cold nights at camp.

BB pick: WoolX Remi Long Sleeve

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Heavyweight wool base layer

When conditions are especially cold, I swap my standard wool base layer for a thicker merino layer that adds extra heat retention to my setup. In cold weather, this still works as a hiking layer, but it’s also a superb nighttime layer when temps drop way below freezing. In almost all instances, I choose between the wool base layer above and this heavy wool base layer when packing for a trip.

BB pick: Smartwool Classic Thermal Base Layer Top

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Lightweight fleece mid-layer

A lightweight technical fleece hoody is the perfect mid-layer for light to extreme conditions, and I find I bring this layer on almost every trip into the mountains. It works beautifully over a base layer AND under heavier fleece or an insulated jacket, adding noticeable warmth without feeling bulky. Ideally, this layer will have a hood and balaclava-like design to further seal in warmth around the neck.

BB pick: Arc’teryx Rho LT Hoody

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Heavyweight fleece mid-layer

A thicker, cozier fleece with a more relaxed fit is excellent for layering over the top of a base layer and, in even more intense cold, over both a base layer AND a lighter fleece layer. This should be stretchy enough to hike in, comfy enough for camp, and ideally a crew or zip-neck (so you’re not collecting too many hoods).

BB pick: Arc’teryx Kyanite Zip Neck Top

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Synthetic insulation

Warmer than a fleece but less delicate than down, a synthetic insulation layer is ideal for unpredictable weather, damp conditions, or high-exertion alpine days. I throw it over my base layer for chilly mornings, wear it under a down and shell in alpine conditions, or use it as my “active insulation” when I’m on the move in cool temps. It’s not as warm as down, but way more versatile— and it doesn’t matter if it gets a bit sweaty or wet. I rarely skip this layer in my packing and usually choose one down jacket to pair overtop.

BB pick: Arc’teryx Atom Hoody

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Mid-weight down jacket

Down insulation offers the best warmth-to-weight ratio of any layer, but it’s also more delicate and less versatile than synthetic. This isn’t the jacket you hike in (unless it’s really cold), but it’s incredibly effective when you’re resting, hanging at camp, or facing cold, dry summit conditions. I usually wear this over at least two layers (a base layer and a fleece/synthetic jacket), and it’s what I reach for when I want serious warmth without a ton of bulk.

BB pick: Arc’teryx Cerium Hoody

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Heavyweight down jacket

This upgraded down layer is warmer, bulkier, and heavier, with more down fill and loft to trap maximum heat. I usually choose between this and my mid-weight down jacket depending on the trip, but in extreme alpine conditions (like Aconcagua), I’ve layered both together with great success. Make sure it fits comfortably over 3-5 layers— this is the outermost piece in your system when you’re in dry cold down to -25C.

BB pick: Arc’teryx Thorium Hoody

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Shell jacket

A shell jacket protects you from wind, rain, and snow, while still allowing heat and moisture to escape from your layers underneath. In moderate but wet weather, you might be wearing this jacket over as little as a t-shirt, but in extreme alpine conditions, it could be layered over 3-4 base layers, fleece layers, and synthetic or down layers— this may require you to size up slightly to accommodate bulky layers underneath.

BB pick: Arc’teryx Beta SL Jacket

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Wool base layer

My go-to base layer for cold weather hiking, alpine layering, and staying warm in the tent, merino wool tights are soft, stretchy, and light enough to wear under just about any pair of pants. I’ll usually choose either these or lightweight fleece tights, but not both; in colder conditions, they also layer well under the heavyweight fleece tights for added insulation.

BB pick: Arc’teryx Satoro Merino Wool Base Layer

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Lightweight fleece mid-layer

Next up is a breathable, stretchy fleece tight that adds just the right amount of warmth when wool alone won’t cut it. I wear them on their own for cool-weather hiking or layer them under the Gamma Pants and/or a hardshell when temps drop further. If I’m not packing my wool base layer, this is usually what I reach for instead.

BB pick: Arc’teryx Rho Base Layer Bottoms

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Heavyweight fleece mid-layer

The warmest and coziest bottoms in my kit. I bring these for cold expeditions, snowy basecamps, or high-altitude trips where I’ll be moving slower or spending time in freezing temps. They layer easily over a merino wool base layer and under softshell pants, creating a system that adapts well to extreme cold; I will hike, climb, and sleep in this 3-pant combination when temps require.

BB pick: Arc’teryx Kyanite Base Layer Bottoms

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Lightweight soft shell pants

These are my go-to lightweight pants for summer alpine climbs, shoulder-season hiking, or any trip where I want breathability and freedom of movement without sacrificing durability. In warmer conditions, I’ll wear these on their own; in moderate weather, I prefer to layer over my merino wool base layer for a bit of added warmth.

BB pick: Arc’teryx Gamma SL Pants

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Mid-weight soft shell pants

These are the pants I reach for on cold-weather hikes, mountaineering in mixed conditions, and glacier travel. They’re warmer, more wind-resistant, and more structured than a lightweight pant— ideal for high-elevation environments or big mountain days. If I’m wearing these, I always have a merino wool base layer underneath, and in extreme conditions (like -20C), I’ll add a fleece layer too. This type of pant is incredibly versatile on its own, but not fully waterproof, so if there’s sustained precipitation or intense wind, a hard shell is going to be necessary on top.

BB pick: Arc’teryx Gamma Pants

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Hard shell pants

These are your outer layer for when the weather turns wild. Hardshell pants are fully windproof and waterproof, designed to protect your lower half from snow, rain, and alpine winds. I don’t always pack them— but if the forecast calls for storms, deep snow, or sustained exposure, they’re essential. If I reach for this layer, it’s pretty much guaranteed I’m already wearing a base layer and/or fleece mid-layer under soft shell pants, so they need to be sized to fit over the top of 2-3 layers without being too restrictive.

BB pick: Arc’teryx Beta Pants

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Buff (neck gaiter)

My favourite multi-use item that lives permanently in my pack as a neck warmer, headband, sun shield, or makeshift balaclava for everything from summer hikes to alpine summits

BB pick: Buff Original + Buff Polar

Beanie

For cold nights at camp and breezy alpine starts, a lightweight and low-profile beanie is absolutely key— for climbers, this should be able to fit under a helmet and layer over a lightweight fleece hood for extra warmth

BB pick:  Arc’teryx Mallow Toque

Sun gloves

Great for long alpine climbing days on snow, these offer sun and ice protection without overheating and can be layered under larger gloves/mittens as an ultralight base layer

BB pick: Outdoor Research ActiveIce Chroma Sun Gloves

Lightweight liner gloves

Essential for even the most basic of hiking trips as a thin but powerful barrier against cold air and wind, but also ideal for layering under larger gloves/mitts in alpine conditions, providing some lightweight protection on a windy summit, or even for cooking dinner at a cold camp

BB pick: Outdoor Research Trail Mix Gloves

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Leather mountaineering gloves

A mountaineering essential that does not apply to casual hikers, leather gloves should be durable and rugged for rope handling and ice axe use, possibly also worn over sun gloves or liner gloves 

BB pick: Outdoor Research Stormtracker Gloves

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Waterproof shell mittens

Ultralight and versatile, shell mittens can be worn over any liners to add snow, wind, or rain protection to the system— these are awesome even for casual hikers who sometimes encounter precipitation at lower elevations

BB pick: Black Diamond Waterproof Overmitts

Insulated mittens

This layer is overkill for all but the most extreme, high-elevation climbs (like Aconcagua), but in these instances, down-insulated, weather-sealed mittens are essential to protect against frostbite

BB pick: Black Diamond Super Light Mitts