My current climate in Georgia is colder than my previous experience in Oregon. We had a very cold morning recently that approached freezing and it allowed me to try out some warmer clothing on my commute. I wore lightweight wool boxers(4oz) under medium-heavy weight wool tights (9oz) with DeFeet Wooly Boolie Socks. Up top, I had a lightweight wool long sleeve shirt (4oz) with a cotton dress shirt over it. I wore Pearl Izumi Impact gloves. Under my helmet I had on a Gore Bike Wear windstopper cap. I was so warm that I ended up unbuttoning the dress shirt about 3 miles into the ride. In the future I'll probably just add a second layer of 4oz wool shirt and put the dress shirt into my panniers.

So, judging by how warm I was, roughly 8-9oz of wool seems to be warm enough for me in dry windy weather down to about 20F. I'll be looking to add a 8-9oz wool longsleeve shirt for days I don't want to layer, and some warmer gloves just in case. I figure if it rains, I'll just put my standard summer rain gear on top.

My advice is that wool is warm, and Gore Windstopper works well.