Layering for Warmth

Now that fall is upon us, it’s a good time to start thinking about your layering strategy for the cold weather. I recently took a camping road trip through the Atlantic states and provinces, and encountered cold weather along the way. On this trip, I was able to test out my layering strategy early and was pretty happy with how it worked out.

Why Layers?

Layers are a great way to keep warm while adjusting to changing conditions throughout the day. Typically, layers also allow you to keep warm with less bulk — you can choose pieces that are best at one thing rather than having one piece that does it all pretty well.

Sweat is the biggest enemy to warmth. Without the ability to shed layers as you warm up, you will sweat, and as sweat evaporates it cools. A sweaty shirt or jacket on a cold day is a quick way to get uncomfortably chilled, or even worse, hypothermia.

How to Layer

My layering system consists of a thermal baselayer, a shirt and/or insulating midlayer, and a shell for wind, rain, or snow.

Baselayer

The most important aspect of a good baselayer is how well it wicks sweat and how quickly it dries. This is to protect from our number one enemy in the cold, moisture. While a baselayer also will help keep you a bit warmer when you are static by trapping some body heat, its real purpose is to help manage sweat when you are active.

Since a baselayer needs to be able to efficiently wick sweat, it is important to get the fit right. You want the fabric to sit snugly against the skin so there is no opportunity for sweat to pool against the skin or for cold air to evaporate sweat directly from the skin.

I typically wear a Patagonia Capilene Midweight Zip-neck and Pants (Polartec Power Grid) as my baselayer. All the Capilene baselayers are treated with Polygiene odor control which I find to work pretty well — I can get a few days out of a top and more out of the bottoms, depending on how much I’m sweating. There also are lightweight and thermal weight options if you need less or more warmth.

For 2018, Patagonia released a new merino blend Capilene, the Capilene Air (51% merino, 49% recycled polyester). The fabric has an interesting 3D knit structure and claims to have the greatest warmth range along with the ability to insulate while wet, dry quickly, and resist odor. While double the price of the equivalent Capilene Midweight, this seems like it could be a great fabric and worth the premium for some.

Midlayer

The main job of a midlayer is insulation. The temperature and whether you are going to be active or static can help you choose the most appropriate piece. Active insulation is designed to be very breathable (air and moisture permeable) so the sweat that is absorbed by your baselayer and evaporated by your body heat is able to efficiently migrate into the environment. Static insulation is designed to keep you warm while you are still, so it is less breathable to help conserve the captured body heat. One thing to keep in mind if you are looking at down — while synthetic insulation still works when wet, down looses much of its insulation capability in wet conditions.

Fit is important here as well, but remember to size for the range of layers you may be wearing underneath. Drawstrings, Velcro, and elastic can help with getting the fit adjusted perfectly.

I typically wear one or two midlayers, depending on weather conditions and what layers I plan to shed if I get warm (or end up inside). For me they can be a long or short sleeve shirt, light fleece (Patagonia R1 Pullover), and/or down jacket. Typically I wear a shirt over my baselayer if I think I might get very warm or end up inside. My insulation layer then goes over either the shirt or directly over my baselayer. An alternative to the down jacket could be a synthetic insulated jacket like the Arc’teryx Atom LT or synthetic active insulation layer like the Arc’teryx Proton LT.

Shell

A shell is an important layering piece when it is windy or wet. Just like sweat is the enemy, getting wet is just as bad. Being wet in the wind is even worse because the wind accelerates evaporation (and therefore cooling). A good shell will protect you from both elements. However, you should not wear a shell unless it is needed because it will typically be your least breathable layer and will hinder the evaporation or sweat. As the sweat builds up and makes your insulation layers damp, it can hinder the ability for them to continue to perform as expected.

For a shell, the fit needs to be more flexible since you will probably wear it on its own as well as over various layers. This makes drawstrings, Velcro, and elastic important so the fit is adjustable.

I prefer a lightweight shell like the Outdoor Research Helium II Jacket because it packs down small for easy stowage when the weather improves (or to carry just in case). The Helium is an ultralight shell, so unlike a hardshell the waterproof membrane is visible on the inside of the jacket. This makes it lighter but less durable and can more easily loose breathability from having clogged pores from body oils and dirt (hardshells typically sandwich the membrane between two layers of fabric). No matter what type of shell you have, if the DWR fails and the face fabric wets out, you loose all breathability.

Utilizing a shell for wind and water resistance allows you to select a very breathable midlayer which becomes especially important if you are active while out in the cold. If you are going to be out in rain all day (or days) or need more durability you might want a true hardshell, but I’ve never had any issues with the Helium Jacket.

Conclusions

If you want to stay warm outside in cool and cold weather layering is the way to go. You can stay comfortable throughout the day, even with changing conditions, and you don’t have to deal with that bulky winter coat for most weather. A simple system of a thermal baselayer, an insulating midlayer, and a shell can get you through most weather. If it’s really cold, you can swap out your midlayer, wear a warmer baselayer, and/or replace the midlayer and shell with a parka.

Layering for Warmth