The one thing to always keep in mind about mountain weather is that it doesn’t have to be the middle of winter to think about the impact of cold temperatures. Depending on the region and elevation, you may encounter drastic changes in weather any time of year. New Englanders find it’s not uncommon to feel like you’re traversing four seasons when climbing New Hampshire’s Mount Washington. Unpredictable temperature swings can make your outdoor activity uncomfortable, or worse, cause a serious injury or illness. For example, it’s possible to get hypothermia, even in summer, when wet or sweaty clothes are chilled by heavy wind.

That’s why the art of layering becomes your body’s smart-technology thermostat any time you plan long stints outdoors. This age-old strategy lets you regulate comfort by adding or taking off layers as your activity level or the weather fluctuates. Air is a poor conductor of heat, so layering allows you to trap warm pockets of air around your body. The right layering system also helps pull moisture away from your skin and keep the harsh wind and wet elements out.

Each layer is important and provides its own protection

Base Layer

The base layer which is the first one against your skin, manages the moisture that your body heat gives off. Because it is meant to wick away sweat during activities, your base should never be cotton. As a material, cotton will absorb moisture, hold it against your skin and can cause chills. Your base layer should be lightweight and made of a synthetic material or merino wool. It should be lightweight enough to wear for inside activities, but not warm enough to be worn by itself outdoors in the spring. Finally, a base layer should fit snugly against the skin but not so much that it hampers the way you move.

Mid Layer

The mid layer, usually a fleece, goes on top of your base layer, keeps the cold out and your body heat in. Think of your mid layer as your insulation from the cold. The mid layer is meant to trap air during your activities and keep you warm and toasty, so the fit should be close to the body, but not so close that you can’t flex and move easily. A down vest also works great as a mid layer to keep your core warm while allowing your arms full mobility. If there’s little precipitation to worry about, some mid layers will even work as an outer layer. Terracea mid layers are highly wind and water resistant as well as highly breathable. They’re also finished with Durable Water Repellent (DWR) for combating wet weather. DWR keeps the material from becoming saturated with water and adding weight, causing water to bead-up and roll off the fabric.

Outer Layer

The shell layer or outer layer shields you from the elements keeping wind and water out. The material should be waterproof, windproof and also breathable. A fully waterproof outer shell will leave you soaked on the inside if it can't wick sweat away from your body. Terracea outer layers come in insulated and non-insulated weights. Our shells are waterproof to 20,000 mm, a high standard that means it can withstand 20 meters of water poured onto it before moisture penetrates the garment. Both our insulated and non-insulated shells are rated at 34K+ breathability, which is defined by how much water vapor can move through one square meter of fabric (from inside to out) in a 24-hour period. They are also fully windproof with taped seams and have the same Durable Water Repellent (DWR) finish as our mid layers.

Always bring all layers

Even if you don’t wear all three layers from the beginning of your outing, it’s always a good idea to take all layers with you for easy access. You can peel off layers if your body heats up, but you can’t put on layers that you didn’t bring along. Have fun out there and happy layering!