100% Merino wool upper and lower baslayer. Mid or lightweight
Cotton canvas "duck" midlayer, like Carharts or Dickies.
Windproof and or waterproof outerlayer.
I would reccommend a soft shell type of outerlayer, unless you are in rain ALL THE TIME , Like Eugene, Portland or anywhere along a coast. In that case, get a cheap layer of Grundens rain Jacket/pants. Like 50 bucks.
And cheap softshell is fine. Best company for the price of merino wool is Merriwool.
Gloves are always recommended. You dont have to get anything bombproof or anything, just something semi windproof.
Also recommended is a neck gaiter (like a balaclava), a beanie (synthetic), and boots.
That will give you a clothing system that will keep you warm from 80 degrees, down to below freezing. It doesn't weigh much, and all you gotta do is remove/add layers.
COTTON KILLS!!