Here is a breakdown of the clothing you will require when trekking unto Everest Base Camp or on the Annapurna Circuit. Much of it will be on hand in Kathmandu, Namche Bazaar, Pokhara or Lukla, but what appear to be genuine labels are going to be nothing of the sort and equipment that is cheaper will frequently not stand up to the degree of cold you will be experiencing.
Layering is key because the weather is changeable, even more so when your altitude is: Lukla stands at 9,383 feet while Kala Patthar is 18,373 feet up. You should also bear the season in mind. You have three layers to consider. For detailed information on these layers check out http://www.trekkinginnepal.org/everest-base-camp-packing-list/ or http://www.trekkinginnepal.org/annapurna-circuit-packing-list/
The base/first/next-to-skin layer is crucial at higher altitudes but likely to go unused lower down. Airflow is lessened when this layer is tight against the skin. The material should be high-wicking to allow moisture to disperse.
The second, insulation layer should be made of fleece. You might not need this for your legs. For your torso, the Polartec 200 Fleece Jacket is warm, lightweight and breathable. 100s are too light and 300s, too heavy.
The third, outer core layer should be a warm and waterproof jacket/trouser pair sure to be indispensable at higher altitudes. One upmarket option is North Face’s Nuptse Jacket and a more downmarket one is the North Face Resolve Jacket. The Nuptse will last so long that its cost could be sustained. Trousers need to be warm and fleece-insulated ski pants as purveyed by Trepass, O’Neills and Helly Hansen.
As well as this layer trinity, you will want trekking shorts to wear of an evening. It might rain, especially during the monsoon season between June and September, so you will wish to possess lightweight rain gear or, at a bare minimum, a poncho. Do not take jeans because they take forever to dry and are decidedly uncomfortable while trekking. Avoid cotton at all costs since it takes in moisture.
Then there is your headwear. A hat to shield your head and neck from the sun cannot be lived without – something light that fits nicely in your daypack. A headband, known to some as a beanie, will be of great use when it turns cold late in the afternoon or at the start of the evening, and more so as Base Camp draws closer. North Face and Berghaus are quality suppliers. Sunglasses that reduce light by at least 80 percent are also indispensable, and Julbo makes them.
Gloves are a necessity. Your outer gloves need to be very, very warm, not to mention durable and waterproof, for example Dakine’s Gore-Tex gloves. Your inner gloves should be quick dry and lightweight, like Pearl Izumi Thermal Lite Gloves. Weather permitting, you will not need the outer gloves.
It is your feet that will be taking you to Base Camp and back. If your boots fit improperly, sore feet, blisters and lost nails are sure to follow. To test the fit, place your foot in the boot with the laces loose and slide it to the front, whereupon you should be capable of inserting one finger. Full leather boots will probably be too heavy. Don trainers in-camp. You will need four or five pairs of trekking socks, as manufactured by Coolmax. Another two pair of thermal socks will see action on colder days close to Base Camp. Smartwool’s thermal socks are one example.
For further information check out http://www.nepalmountaineering.org/