The biggest mistake that new winter hikers make is overdressing by wearing heavy or medium-weight baselayers that are hard to remove if you start to sweat. You’ll be much better off wearing a very thin crew or quarter-zip shirt and adding additional thermal or wind-blocking layers on top of it if you start to feel a chill.
For example, you can exert a finer degree of control over your warmth level if you wear a lightweight baselayer top instead of a medium or heavy one and then add a second lightweight top over it if you start to feel a chill. There’s virtually no weight difference clothing-wise in this approach, but it gives you a much finer level of control over how warm you want to be when hiking in winter.
Perspiration is Bad
The problem with being too warm in winter is that it causes you to perspire. Perspiration is bad because it burns more calories, but that’s a hard concept for most people to understand and internalize. A more obvious outcome is that perspiration causes the air pockets in your clothing to clog up with liquid. This reduces the size of the air pockets in your clothing that trap warm air, reducing their ability to insulate you.
Some perspiration is inevitable, even when your body is at rest. Called insensible perspiration, you’re body emits about 400 ml of water per day through your skin. The Greeks were the first people to observe this fact thousands of years ago.
While you can’t completely stop perspiration, you can manage the degree that it degrades your clothing’s insulation value by wearing hydrophobic clothing that transports any water it absorbs away from your skin. This approach, commonly called layering, is best accomplished by wearing thin, highly porous clothing next to your skin. When layering, you want to preserve that wicking action through as many layers as possible. The goal is to move moisture from your skin to an outer layer where it can evaporate.
For example, I use three core layers in my winter hiking layering system:
- A thin lightweight long sleeve jersey, usually synthetic.
- A lightweight fleece hoody
- A nylon windbreaker
That’s it, down to about 15 degrees. I can tell it’s working because the underarms of my wind shirt are damp and stinky at the end of the day. That means my perspiration is evaporating from the outermost layer.
The Next-to-Skin Layer
I’ve found that the most important garment in my layering stack is the foundational next-to-skin garment. Look for tops that you can see through when you hold them up to the light. I prefer synthetic long sleeve tops because they don’t absorb as much moisture and are very effective at wicking moisture up to my next layer. Wool can work too, especially wool garments that combine synthetic and wool yarns because they wick like synthetic tops but smell less due to their wool content.
Here are the next-to-skin tops that I use and that you might find useful to try.
- Patagonia Capilene Lightweight Long Sleeve Crew (synthetic)
- Helly Hansen Lifa Stripe Crew (synthetic)
- Nike Dri-Fit Long Sleeve T-Shirt (synthetic)
- Brynje Thermo Mesh (wool or synthetic, very good for extreme cold)
But I can’t stress this enough. Keep that next-to-skin layer thin so that moisture can move quickly through it and up into your next layer. While it’s not intuitive, you’ll stay warmer if you stay cooler and perspire less during the course of the day.