When recreating outdoors in Montana one must dress for the weather and the possibility of changing weather conditions. If you are recreating very close to home, so that you can get out of the weather if it changes suddenly, you can dress for the current weather. When you are going to be recreating an hour or more away from protection from the elements you need to be more cautious about your clothing choices, for your comfort as well as your safety. In these cases you need to bring what you need, planning ahead for the unexpected.
Be comfortable, stay safe, and have fun in the outdoors!