Well I?ve returned from my trip to Colorado. We fished on South Boulder Creek west of Pinecliffe, Colorado (~9500 feet). Given the forecast, I decided to pick up a pair of Simms Rivertek Grid Fleece pants to wear under the waders ? paired with merino wool socks. I?m glad I did as it snowed all day long! The temps were just below freezing all day but the fishing was awesome! On top, I wore a light polypro baselayer, a merino wool pullover, a Patagonia micropuff, and a rain jacket. It was a perfect system - no cold spots, no sweating. Thanks again for the input. Brian