Rain gear, a puffy jacket, and puffy pants, dry socks, warm gloves and hat are essential. I won't leave my truck without them during archery season in CO. That picture of the snowy tent is a clear indication of what it's like early season at high altitude. We actually hiked in during that storm in 2020, and if we hadn't had rain gear, warm, dry clothes, and good shelter, we would have been in big trouble. It took a day running the woodstove in the tipi to dry all our gear out, and we both had top of the line rain gear, which still managed to get wet eventually because of the volume of wet snow coming off the trees as we climbed through them. At the absolute bare minimum have a poncho and an emergency bivy in your pack at all times. I've had to sleep out in just my army poncho and the clothes on my back during archery season, when I was younger, and it was a lifesaver having something waterproof, and windproof to protect me.