I find a rain jacket/wind breaker is essential and I find jackets made from Propore give the widest range of comfort as it does block the wind 100% and offers a nice insolating pocket of air when it’s cold. And when it starts to get warmer it is somewhat breathable so it takes a long time for the “internal” heat to build up to sauna proportions.

http://www.rei.com/online/store/Prod...8000&langId=-1