What will the weather be like?
Weather in the Rockies is highly unpredictable. Daytime highs can get up into the 80s and nighttime lows can dip down below freezing. The key is to think in layers and be prepared for anything. Summer usually also brings afternoon thunderstorms, so having an easy way to stay dry is essential. I prefer a poncho for this since it is so light weight and easy to get on and off.