Baselayers are an essential part of a winter layering system. These next-to-skin layers set the foundation for your entire system by providing core warmth, body temperature regulation and moisture wicking properties. You should select your baselayers by accounting for whether you are doing high output or slower-moving activities, expected temperatures and weather conditions, as well as personal preference.
Baselayers typically come in different weights that determine how warm they are. For example, Smartwool makes lightweight and midweight variations of their wool baselayers, while Terramar produces three different weights of their synthetic baselayers. If you are engaging in a high-output winter activity like trail running or nordic skiing, opt for a lighter weight baselayer. Conversely, if you are Alpine skiing at a resort, ice climbing on a cold day, or out for a short hike, a heavier and therefore warmer weight baselayer will keep you warm. The outside temperature is also important to note when choosing what baselayer you need on a given day, since you may need a heavier layer for trail running if it’s in the single digits, while you might want a light baselayer when Alpine skiing on a sunny, 40 degree day.
Additionally consider how warm or cold you usually are when you are outside in the winter. Some people who are always cold may need a heavier baselayer even when moving, while ‘warm-blooded” folks could wear with a midweight baselayer and be comfortable on a zero degree day at the ski resort. It’s a good idea to have a set of lightweight baselayers and a set of mid or heavyweight baselayers so that you have different options when building your layering system.
Merino wool is an excellent choice for a set of baselayers. Wool is a natural, renewable performance fabric that is highly breathable, naturally anti-microbal (doesn’t stink), moisture wicking, and has a high warmth per weight ratio. Modern Merino fabrics are soft and don’t itch, and are naturally high performing materials. Compared to synthetics, wool products smell better, feel better on the skin and are generally warmer. Wool also has excellent temperature regulation properties, so that you can use a Merino wool baselayer piece for a much wider temperature range compared to synthetics and remain comfortable. Learn more about wool from our blog post on Merino wool apparel.
Baselayers made from synthetic fabrics still have some excellent performance properties that make them worth considering. One of the major advantages of synthetics over wool is durability. Wool fibers are delicate and will wear out more quickly than synthetics. If you are tough on your gear or if you are doing something active that could potentially damage your baselayers over time, opt for synthetics. Additionally, if you are participating in a high-output activity where you know you will be sweating, synthetics are a good choice as they dry faster than wool. Synthetics are generally cheaper, so if you are purchasing multiple weights or putting significant wear on your baselayers, synthetic pieces may be better for your wallet.
Styles of baselayers:
In addition to the various weights and material constructions that constitute baselayer pieces, there are also a few different styles of cuts to choose from, each with its own set of benefits.
Short sleeved- Short sleeved baselayers are versatile, as they can be used all year. A wool or synthetic short-sleeved layer will wick sweat and warm the body’s core. A short sleeved layer does not hinder mobility, however on very cold days it may not be enough.
Long sleeved crew- A long sleeved crew neck adds warmth and wicking capabilities to the arms. A long sleeved crew is a good all-around cold weather baselayer for a variety of activities.
1/4 zip or 1/2 zip long sleeved- A baselayer with a zipper adds versatility. In addition to long sleeves that provide warmth throughout the upper body, the layer can either be zipper fully, which adds coverage for the neck, or unzipped for excellent venting. A 1/4 or 1/2 zip baselayer is ideal for backcountry skiing, or other activities that combine high and low output movement, or for variable weather conditions.
Hoody- Some baselayers have a hood, which can be used to provide maximum coverage underneath a helmet or hat during severe weather conditions. Hooded baselayers are not as common as hooded midlayers however, which can achieve the same results without hindering versatility.
Baselayer bottoms are far simpler than tops, but do come in a few variations. In addition to basic full length tights in wool or synthetic, you can also select baselayer bottoms that are cut for a ski or mountaineering boot and fall around the middle of the calf. There are also various thermal tights available, that are worn as a next-to-skin layer, but are extra warm and can be used alone or with shorts over them. For basic, all-around baselayer bottoms, select a full length wool or synthetic pair in an appropriate weight.