How to pack clothing for high-altitude trekking

Pack using a strict three-layer system: a synthetic base layer, an insulating mid-layer, and a windproof, waterproof outer shell. Focus on wool or synthetic materials, as cotton will retain moisture and cause you to lose body heat rapidly once the sun goes down.

1. Layer for variable temperatures. Bring a moisture-wicking base layer (merino wool is best), a fleece or down jacket as your mid-layer, and a hardshell jacket for high winds. You should be able to peel these off or add them on within 30 seconds.
2. Prioritize extremities. At high altitudes, thin air means less protection from UV rays and rapid heat loss. Pack a warm beanie that covers your ears, a neck gaiter (buff), and two pairs of thermal gloves—one thin pair for dexterity and one thick pair for warmth.
3. Select the right footwear. Bring mid-cut, waterproof hiking boots that are already broken in. Pack three pairs of thick wool socks; moisture management is critical to prevent blisters and cold feet at altitude.
4. Protect against intense sun. High-altitude sun is aggressive. Pack a wide-brimmed hat, polarized sunglasses with side protection, and lightweight long-sleeve shirts that offer UV protection.

Why can't I wear cotton?

Cotton absorbs moisture and dries very slowly. In high-altitude environments, if you sweat while hiking and then stop, the damp cotton will pull heat away from your body, significantly increasing the risk of hypothermia.

How heavy should my pack be?

Try to keep your total pack weight under 15% of your body weight. At altitude, every extra pound feels like three because of the thinner air.