The safest, and most comfortable, way to dress in the outdoors in Montana, is in lightweight layers. This gives you the ability to add or remove layers in response to changing conditions, and lightweight layers are generally smaller and easier to pack.
Keep in mind that dressing for outdoor activities is much different than dressing for home or short outings to the store or office. When you are recreating outdoors your clothes should allow you to move freely and comfortably. You may sweat so your clothing needs to wick the moisture away from your body to keep you dry. You also have to be prepared for changing weather conditions.
The inner layer, worn next to the skin, is intended to keep the wearer comfortable and dry in warm conditions and retain warmth in cold conditions. This layer should be made of a material that wicks moisture away from the skin and provides insulation. Clothing options are available in a variety of thicknesses for different activities and weather conditions.
Mid-layer garments are intended to provide insulation and warmth when needed. This layer may vary from a lightweight shirt in warm conditions to a warm shirt and a fleece or wool pullover in cold conditions. The mid-layer or layers, may vary drastically depending on the time of year and activity level.
Outer layers are used to protect the wearer from wind and precipitation. These garments are generally made from wind resistant, water resistant, or water proof fabrics. They may also add insulation.