Now that we have the packing process down, what about the clothing itself? In cold temperatures, layers are your friend. Cotton may feel good, but there is a reason for the phrase “cotton kills.” Cotton is bad at regulating body temperature, stays wet, and can lead to hypothermia. Merino wool layers (like these from Smartwool) are fantastic for regulating body temperature. They are moisture-wicking, quick-drying, and odor resistant. You can wear them repeatedly and no one will be the wiser. The material is also soft enough for skin sensitive to wool, though a synthetic performance shirt can manage the job similarly.
The midlayer, which goes over your baselayer, helps you stay warm while keeping things breathable. In chilly, but tolerable conditions, your midlayer might be the only thing you need. It can be as simple as a quarter-zip fleece from Eddie Bauer, or in colder weather, a down puffer or synthetic jacket. Down is good for staying warm without being heavy. Synthetic insulators are an alternative to down. Self-packing jackets—those that pack into a pocket—are useful when packing space is at a premium.
If your midlayer isn’t waterproof, then the outer layer, like a shell, will protect you from wind, rain, and snow. Shells can fit over a midlayer jacket, though there are also jacket-shell systems, where you can get the two together, and wear either one layer or both together depending on weather.
