Winter Backpacking Clothing

Winter clothing in Southern California means being ready for 80 degree days, 30 degree nights, Santa Ana Winds, rain, snow and sunburn. The best way to cope with this is synthetics and layering. This way you can add or remove layers and avoid getting sweaty and soaking your clothes.
Using synthetic fabrics for your insulating layers mean that they won't hold water and stay cold like jeans or sweats will. Having an outer layer of nylon keeps the Santa Ana winds from blowing right through you.

On every hike you should have:

Synthetic underwear
Nylon running shorts
Synthetic (not cotton!) long underwear pants (long johns)
Nylon running pants (athletic kind that resemble sweat pants-leg zippers allow you to put them on without taking your boots off)
Cotton T-shirt (feels good on hot days, and doubles as a pillowcase)
Synthetic shirt
Fleece jacket with hood
Nylon windbreaker
Sun Hat with a wide brim ("Boonie" hats are our favorite)

Fleece booties with hard soles for around camp
Extra pair of polartec fleece socks
Thin nylon socks (white socks look dirtier: get colored)

Wear most of your clothes to bed: why carry both heavy clothes and a heavy sleeping bag?

In cold weather, add:

Synthetic long underwear shirt
Polartec fleece pants
Insulated waterproof/breathable parka
Knit watch cap or "beanie"

Cotton square-foot sleeping bags are for Girl Scout slumber parties and padding moving vans.

Nighttime calls for a mummy sleeping bag made of synthetic material. The same goes for your sleeping bag as your clothes: cotton bags are freezing when they get wet. Plan on at least 5 lbs. of fill weight when choosing a winter bag. In snow camp or extreme weather, nest two bags inside each other.