Base Layers
Base layers are the foundation of any effective cold-weather layering system. Worn next to your skin, these moisture-wicking garments keep you dry, warm, and comfortable by moving sweat away from your body. From merino wool to high-tech synthetics, quality base layers are essential for staying comfortable in cold conditions.
Best Base Layers
Top-rated thermal underwear and merino wool base layers
Smartwool Merino 250 Base Layer Top
Patagonia Capilene Midweight Top
Arc'teryx Rho LT Base Layer
Smartwool Merino 250 Base Layer Bottom
Patagonia Capilene Midweight Bottom
Icebreaker Merino 200 Oasis Top
Understanding Base Layer Weights
Lightweight
Lightweight base layers (100-150g) are perfect for active pursuits in mild to moderate cold. They provide minimal insulation but excellent moisture-wicking for high-intensity activities.
Mid-Weight
Mid-weight base layers (200-250g) offer a balance of warmth and breathability. Ideal for moderate cold and mixed activity levels, they work well for most winter conditions.
Heavy-Weight
Heavy-weight base layers (250g+) provide maximum warmth for extreme cold or low-activity situations. These are essential for very cold conditions or when you'll be stationary.
Frequently Asked Questions
A base layer is the first layer of clothing worn next to your skin. It wicks moisture away from your body, provides insulation, and helps regulate body temperature. Base layers are essential for staying warm and dry in cold weather.
Merino wool is considered the gold standard for base layers due to its excellent moisture-wicking, natural odor resistance, and temperature regulation. Synthetic materials like polyester also work well and are often more affordable. Avoid cotton as it retains moisture.
Base layers should fit snugly against your skin without being constricting. This allows for effective moisture-wicking and ensures the layer works properly. Too loose and it won't wick effectively; too tight and it will be uncomfortable and restrict movement.
