When I climb or hike in extreme or quick changing weather conditions here is what I wear:

Outer shell: Arteryx GoreTex jacket.
Inner Layer (warmth): Arteryx heavy flece
Inner Layer (wind chill): Mountain Hardwear windstoper
Moisture Whicking Layer (t- shirt): North Face Moisture Guard shirt

In my pack I also have a rolled Down filled vest.

Pants are usually cargo canvas pants and I have goretex pants in my backpack as well just in case.

I love smartwolls socks and on my recent trip to Peru I stocked up on sweaters and long shirts made out of alpaca wool. Wool is warm even if wet but dries forever.

I combine layers and functionality. Just because it's raining it doesn't mean that it has to be cold. When it's cold it doesn;t mean that it has to be wet. Or it can really be cold and wet. Well i can go on with that forever since we all know how unpredicatble weather is. My point is that by having items that serve multiple purpose you are set and never be too hot or too cold. Gortex shell will seal you tight from water and depending on the temperature it can be used alone or with additional fleece it can be made warmer. By layering you can peel off and get comfortable instead of experiencing a rapid shock.

I have a big brim water proof hat. Brim is big enough that water tricks down on my jacket instead of down my neck. But usually if I'm tight on space I use hood from my jacket.

Matt