Softshell jackets are a lightweight, breathable solution for skiers, climbers, and runners. Softshell is a synthetic material that offers weather protection, ample warmth, high breathability, and good range of motion. A fleece jacket will usually provide more warmth and a shell jacket more weather protection, but a softshell strikes an ideal balance between the two.
The more active you are, the more breathable you want your jacket to be. A single-layer softshell offers plenty of breathability, but it sacrifices some weather protection. On the other hand, a two or three-layer softshell jacket will sacrifice a bit of breathability for the sake of more weather protection.
A loose fitting softshell is fine for skiing, but if you’re climbing or backpacking, you’ll want a jacket with a slim or athletic fit. A more contoured fit keeps the jacket close to your body, give you room to layer underneath, and it’ll feel comfortable when you’re wearing a backpack or climbing harness.
With the exception of a couple of pockets, most softshells are relatively bare-bones when it comes to features. Carefully consider what you plan to do in the mountains to determine the exact features you need. Underarm zips or a helmet-compatible hood may be necessary for one activity and unnecessary for another.