My experience since the latter 1960's has been in northern Colorado. I live at 5000 ft and have hunted to 10,000 ft + .
Mountain weather Oct through Nov can go from clear,sunny,and comfortable in your Pendleton shirt and jeans to a white out snow squall in a couple of hours...Or even less if it sneaks over a ridge.
Expect to deal with Cold/wet ,then wind ,and freezing cold...On a day that starts out balmy.
And I've seen visibility drop to about 30 feet as tracks and trails are snowed over. What adds to the fun is that sort of weather blocks satellite signals. The GPS quits.
Your Pendleton shirt is good.
I don't use cotton jeans or the typical cotton based hoodie. Those get wet they might kill you. I will use a PolarTec type fleece hoody.
I'm not concerned about how my costume looks or whether anyone approves.
I need a breathable (semi) waterproof uninsulated mountain parka shell. I say "semi waterproof" because Gore-tex ,etc will leak... but IMO.they are great.They block wind,shed water,and even Alaskan mosquitos can't bite through them. Some of them are noisy. Cabelas sells some that has a soft ,quiet finish.
For a few bucks you can get a GI field jacket liner. They made one for the Arctic Parka that is an even better find, .Its similar to poncho liner construction. Very light nylon shell,thinsulate fill. Thats a cheap,light,versatile layer. It wont hold water. You can near dry it swinging it over your head. I have an assortment of useful layers,I don't carry them all.
Among them might be Poly-Pro base layer underwear,Polartec jacket or hoody,down or poly fill vest or sweater,etc.
Pants? I have a combination that looks funny,and works for me. In high altitude,elk hunting conditions I took a pair of the heavy weight German army surplus wool battle pants ,and cut them off just below the knee, A seamstress hemmed them for me. I added the rivet-on suspender buttons and Carhart heavy duty suspenders. Under those I have PolyPro long johns covered by lightweight wind resistant running pants. I like that its light weight below the knee and does not absorb water or freeze.
The blanket weight wool "knickers" look funny. OK. They have cargo pockets,and sure are nice for sitting down. They are silent. Not far off from the German Mountaneer's Lederhosen.
I like the Danner Pronghorn boots and Merino wool sox. I use the mesh orange vests. I like light boots.
I don't claim thats the ultimate, but with that ,and of course hat,gloves,etc, I can hunt out of a small tent in a wilderness area at approx 9000 ft in Colorado Oct/Nov for a week at a time. By Wilderness I mean a Wilderness area,and all I have is what came in on my back. There is no going back to the pickup or running to town.
Gear has to be well chosen and it has to work. I know because I've done it. More than once.
Y'all know how to dress yourselves. A lot depends on environment and whether its a day trip and type of hunt. If a tee shirt and jeans works for you,have fun!!