Outdoor Layering Guide February 15, 2024

My personal recommendations for staying warm and dry in the outdoors

General Principles

The goal of layering is to stay comfortable by managing exposure to four factors:

• Ambient temperature
• Wind chill
• Precipitation (rain, snow)
• Perspiration (sweat)

As exertion increases, you take off layers. When you cool down, you add layers.

Your core temperature is the most important thing to manage. If your core falls below 95°F, you become hypothermic. If you get too hot, you are at risk for heat exhaustion.

Your extremities also need to be cared for. While usually not life-threatening, cold hands and feet can significantly impact your ability to enjoy the outdoors.

Exposure to moisture (rain/snow and sweat) will not only make you cold, but reduce the ability of the materials in your clothing to keep you warm. This is especially true for plant fibers such as cotton, hence the phrase “cotton kills”. Avoid cotton T-shirts, sweatshirts, gym socks, jeans/denim, canvas, etc.

If you are going outside for more than just a short hike, you should be prepared for colder, windier, and wetter conditions than what you hope to encounter, and ready to spend much longer outside than planned.

To some extent you can mitigate risk without carrying too many “unnecessary” layers by packing emergency ponchos, shelters, and blankets, but those are usually not very durable, comfortable, or well-suited to long-distance active movement.

Basic Concept

• Your base layer provides insulation and wicks moisture.
• Your mid layer provides insulation and light weather protection.
• Your outer layer keeps out the weather.

A Note About Sweat

One of the four factors that can make you cold is perspiration (sweat). Sometimes when you're starting out on the trail, the air is cold and your muscles aren't warmed up, so you really bundle up. Before you know it, you're getting sweaty and need to stop and take off a layer. The problem is your insulation layers are now not going to do their job as well. So it's often a good idea to start a bit cold and avoid piling on the layers at the start of your trip. However, you should keep a warm layer like a puffy jacket at the ready to pull out as soon as you stop for a break, so you don't lose your body heat. (This idea was pioneered by the "fast and light" school of mountaineering / alpinism.)

All-Day Winter Sports

I.e., mountaineering, snowshoeing, backcountry skiing—activities where you are more than 30 minutes away from your car and/or other people.

The two main approaches to layering for winter sports are “fast and light” and “traditional” (or “expedition”) style. The idea behind fast and light is that you are moving fast and generating a lot of heat, so you wear light clothing until you stop moving (ie, to camp or belay), and then you pile on layers quickly. Whereas the traditional approach is to maintain a more moderate exertion level and wear a more well-rounded set of clothing most of the time. In more extreme (wetter, windier, colder) conditions you really have no choice but to layer up because your body and your gear won’t be able to stay warm and dry all day without the right combination of materials.

Base Layers

Your base layer is your next-to-skin layer. There are two types: synthetic and wool (usually merino). Synthetic fabric (polypropylene, polyester, nylon, spandex) tends to be more resistant to stretching / wear, and is lighter and more wind-resistant. Wool is warmer and more odor-resistant, and insulates better when wet. There are hybrid fabrics that mix and match all of the above as well.

Base layer brands to look for:

• Wool: Smartwool, Ibex, Icebreaker, REI
• Synthetic: Pretty much any athletic apparel brand (Patagonia, Nike, etc.)

Wool socks are the preferred sock for the colder weather. 100% wool socks are warmer and more wet-tolerant than synthetic blends. Good merino wool brands are Smartwool, Darn Tough, and Point 6. You can also get alpaca (from a brand called Paka) or even muskox fiber socks. The Costco brand has a reputation for not being warm because they use too much synthetic material with the wool.

Some sock recommendations:

• Ski Socks Classic Smartwool mid-calf socks
• Hiking Socks Thick crew-cut socks from Darn Tough
• Boot Socks LL Bean ultra-thick socks for winter boots, wellington boots, etc.
• Camp Booties Booties for camp/hut/sleeping bag use. Various brands make these.

Mid Layers

There are a huge range of appropriate mid layers depending on conditions. The main goal of your mid-layer is to keep you warm, and provide light protection from the elements. You may drop this layer as you warm up.

In some cases, the order of layers can be mixed up, like when following using a puffy jacket “belay parka” style (keeping your warmest coat in an easy-to-access place and pulling it out and over whatever you have on already when you stop, rather than taking off your shell layer and putting it underneath).

Fleece

You can't really go wrong with synthetic fleece as your default midlayer, but you might want to switch it out for something more weather-resistant if it ends up being your outermost layer.

Some fleece has a membrane or smooth face finish for wind resistance, and "grid fleece" patterns tend to have pretty good warmth-to-weight ratios.

Recommendations

• Lightweight: Patagonia R1 Air, Rab Tecton, Outdoor Research Trail Mix
• Heavyweight: North Face Denali, Patagonia Better Sweater, Norrona Trollveggen, Earth Sea Sky (NZ) fleece

Synthetic Insulation

Insulated jackets offer better weather protection than fleece, but are less breathable. Synthetic insulation isn't as light or packable as down, but it works better if it gets wet, and can be less prone to losing insulation if you tear the jacket.

Heavyweight synthetic jackets make great belay parkas. Choose a size that you can slip over all your other layers, helmet, and harness, and look for two-way zippers.

Recommendations

• Synthetic Puffy: Patagonia's Nanopuff and Micropuff insulated jackets are the classic in this category, but there are tons of alternatives.
• Stretch/Hybrid: Mammut Rime, Himali Ascent, Jack Wolfskin Alpspitze, Black Diamond First Light, Arcteryx Atom LT
• Heavyweight: Rab Generator Belay Parka, Houdini Dunfri

Down Insulation

Down jackets pack down really well and insulate down to extreme temperatures. But bear in mind they have to be kept dry or they will no longer insulate. Down insulation is described with a “fill power” (FP) rating which refers to the quality of the down. Higher FP = better warmth for weight. FP ranges from 650-1000 with most nicer jackets being about 800 plus some hydrophobic treatment to protect against water. Fill quantity (amount of insulation) ranges from 100-300 grams. The jacket material also matters - most are made of nylon with windstopper treatment (Pertex or Toray). The fabric weight is counted in denier - smaller numbers are very thin and less tear-resistant than larger ones. Typical denier range is 7D - 30D for puffy jackets.

Recommendations

• Light Down (90-120g fill). Rab Microlight, MH Ghost Whisperer. Pretty much every brand makes something in this category.
• Midweight Down (120-200g fill). Rab Electron, Jack Wolfskin Alpspitze, Mammut Broad Peak, Outdoor Vitals NovaPro. There are also more breathable stretch fabric options from brands like Rab and Mountain Hardware.
• Heavyweight Down (200-300g fill). Arcteryx Alpha, Rab Positron, Montbell Alpine Down, Norrona Trollveggen, Himali Altitude.

Vests

A vest can be a nice in-between layer or just a convenient way to keep things organized with extra pockets.

Recommendations

• The Mammut Rime Light vest is a great all-rounder

Softshells

Softshells are designed for breathability, abrasion-resistance, and wind protection. They are treated with water repellent coatings (DWR) but aren't waterproof like a hard shell, so don't go out without at least an emergency poncho if your softshell is your outer layer.

Recommendations

• Black Diamond Dawn Patrol Jacket: Softshell ski/climb jacket
• Stio Upslope Touring Pant: Softshell ski pant, lots of pockets, expands to fit boots. See alternatives from OR, Black Diamond, Arcteryx, and Himali.
• Cross Country Ski Pants: Stretchy, wind-resistant pants that are great for hiking, snowshoeing, as well as their intended use of XC skiing.

Outer Layers

Your outermost layer’s primary job is to protect you from the elements. It may be insulated as well, but many people prefer the flexibility of an uninsulated shell, delegating warmth to base and mid layers.

All-in-One Jackets and Parkas

All-in-one jackets are insulated and weather-resistant. They are convenient because they don't require as much coordination with midlayers so you can just throw them on and go.

However, you lose layering flexibility and these jackets are prone to getting soaked through in tougher conditions and being difficult to dry out. For those reasons, all-in-one jackets tend to be more of a ski resort or around-town layer than a good choice for mountaineering.

Most brands make several types of all-in-one jacket.

Parkas are hooded, wind- and water-resistant coats that extend below the waist. They are not usually designed to be packable. In extreme conditions they are used on top of base and midlayers; in milder conditions (like urban commuting or dog walking) they can be used on their own.

Some jackets/parkas have a removable liner (making them a "3-in-1" system because you can use either the liner or shell on its own).

Recommendations

• Jack Wolfskin Argon Storm Jacket
• I don't have strong rec for parkas other than that Scandinavian brands like Helly Hansen, 66 North, Fjallraven, etc. make good ones

Hardshells

Hardshell jackets are waterproof and windproof. The waterproofness rating is in mm water column - look for 20,000mm or more for serious conditions.

Hardshells tend not to be very breathable, so look for pit zips and other ventilation options. More mountaineering-focused jackets will also be made of more durable materials to resist scrapes and tears.

Solid brands for hardshell gear are Mammut, Outdoor Research, Helly Hansen, Narrona, Arcteryx, Marmot, Rab

Recommendations:

• Hiking Jacket: OR Foray 2. Two-layer Gore-Tex hiking jacket with really good ventilation zips. Costs a lot less than similar options from Arcteryx, etc.
• 3-Layer Shells. These cost... a lot, but they are the gold standard for weather protection. Most 3L shells are Gore-Tex but there are competitors. More skiing-oriented shells will be less durable than mountaineering-focused ones. Look for off-season sales for deals. See Mammut Nordwand, Arcteryx Beta.
• Hardshell Pants or Bib. There are a lot of options here, find ones that fit and have some degree of ventilation. I like full-zip so they are easier to get on and off if wearing boots. You will probably want gaiters to protect the bottom of the pants from ripping.

Extremities

Gloves and Mittens

Go to an outdoor store and get 1 pair of liner gloves, 2 pairs of Polartec weather-resistant fleece, 1 pair of leather insulated gloves or mittens, 1 pair of packable down or synthetic mittens, and 1 pair of waterproof mitten shells that you can put over any of the previous items.

If you are active outdoors you will probably go through more than one pair of gloves a day as they get wet.

Good brands are OR, Rab, Helly Hansen, REI, Hestra, Black Diamond, 66 North, etc.

Gaiters

Gaiters go around your calves and ankles and keep the snow, mud, etc out of your boots.

Outdoor Research makes excellent gaiters for pretty much every condition.

Hats and Scarves

You lose 40% of your body heat through your head, so choose your headwear wisely.

Basic kit:

• Hat with a bill. Even in the winter, a basic “ball cap” style hat is useful for keeping the sun and rain/snow out of your eyes.
• Beanie. Or whatever you call it - a toque.
• Balaclava. Head and neck cover for sleeping, wearing under a helmet, or as a replacement for a hood.
• Scarf/Neck Muff. You can lose a lot of heat if the neck of your jacket isn't well-sealed - a scarf fixes this.

Boots

• Insulated Hiking Boot. In moderate conditions, a waterproof insulated hiking boot is all you need. Most brands make something.
• Midcalf Lace Up. In deeper snow or wetter conditions you may want a taller boot. Check out Sorel, Baffin, LL Bean, and Muck boots.
• Rubber Boot. Rubber boots are also good but don't have as much ankle support. Check out Xtratuf, Baffin, Muck boots.
• Mountaineering Boot. For mountain climbing you need a stiff, waterproof boot that is crampon-compatible. These can be 3/4 shank (more flex) or full shank (very stiff) and ankle- or calf-high.

Winter Layering Scenarios

Backpacking

I'll come back to this in the summer. My main recommendation is to get a big hat and a sun hoodie.