Wearing high quality brands certainly helps, but the real key to staying warm in winter is dressing in layers with the ability to vent off excess heat. The secret is using three layers as follows:
WICKING LAYER: This layer is next to your skin and wicks away perspiration (we all sweat whether we like it or not). Avoid cotton because it absorbs perspiration, becomes damp and stays damp. Natural products such as wool, silk and manufactured materials like poly-propylene and myriad variations of it have the advantage of keeping you warm when they are wet. These latter materials wick the moisture from your skin but retain it as it evaporates allowing you to stay drier.
INSULATING LAYER: Your body provides the heat but wrapping yourself in insulation holds the heat in and keeps you warm. Pound-for-pound, down is the best insulation, but like cotton it must be kept dry to retain it’s loft (puffiness) and keep you warm. Hollofill or quallofill are manufactured down-like materials which retain insulation values when wet. Fleece and pile and their various similar manufactured materials are also warm when wet. Wool is a natural product with the same capability. Natural fur has been keeping us warm since time began.
WEATHERPROOF LAYER: The previous two layers will have minimal value without an outside layer to keep the out the wind and rain. Among the best are Gore-Tex and similar waterproof, breathable garments. A simple, inexpensive, nylon shell works well in most situations and polyester-cotton blend is fine in cold, dry conditions. Any garment used for this layer should fit somewhat on the loose rather than snug side. Often there are laces or elastic in the hood, cuffs and hem.
The outer layers should allow venting. This can be through underarm zippers, opening necks or zippered-sides on pants. Don’t wait until you are cold or too warm to use the venting system. If you pay attention, the vents can be used to keep you in your comfort zone especially during periods of exertion or inactivity.
To stay warm a hat is essential to prevent up to 50 percent heat loss through your head.
Warm hands and feet are critical to your comfort. These are areas where your truly get what you pay for, so do some research and talk to others about what works for them. Poly-pro sock liners under wool are a good start and mitts are generally warmer than gloves. Air-activated hand and foot warmers are cheap and effective.
Preparation is half the battle.