Staying dry starts at the skin, thus the base layer should function like a second skin. When we perspire, moisture evaporates from the skin's surface to cool us, but in cold conditions we need to conserve warmth. The base layer should draw moisture from skin, yet remain dry so we are not clinging to damp fabric. Thermal tops and bottoms made from such fabrics as capilene and thermastat wick moisture away from the body and move it outside the garment. These fabrics dry quickly and resist mildew and shrinkage.
Different weights are available depending on conditions and activity level.
Choose lightweight or medium for moderate conditions and expedition weight for extreme cold or less active endeavors like ice fishing. Add sock and glove liners for feet and hands to complete the base layer. The second layer should preserve body heat and insulate against the cold. One of the best materials for this is fleece. Fleece offers several advantages over traditional fabrics.