I've hiked a handful of 14ers this summer and within 2000 feet of the summit, I have put on a down jacket for all of them. Not only do I keep this down jacket in my pack, but also a synthetic insulated hooded jacket for wet/colder conditions. I've also used this jacket this summer (cold on Mt Tyndall, snow storm on White Mtn, rain on Split Mtn, bivy on Williamson). I also pack light rain shell pants. The extra 2 lbs of clothes is not a big deal, the only other things in my pack are water, food, and first aid.
What I've learned this summer: NEVER underestimate the weather. Be prepared.
