Winter Boot Temperature Ratings
Providing an exact rating for winter boots is difficult because there are so many variables: your sock system, metabolism, fitness, hydration level, food intake, exposure time, activity level, and so on. There is no industry standard for ratings, but we provide manufacturers' ratings when possible. Ratings assume you're actively walking or snowshoeing. When you're idle, the effective warmth of any footwear will drop. If you know from experience that your feet tend to get cold, choose boots that are rated for lower temperatures than those you'll actually encounter.
For lower-output activities in colder temperatures, such as snowshoe walking or winter camping, choose thickly-insulated, calf-high boots with removable liners. These boots have a slightly loose fit, to allow good circulation and extra sock layers. Removable liners are easier to dry out, and are particularly suited to multi-day trips.
For intense activities such as snowshoe running, you might select low-cut boots that have less insulation (some have sewn-in insulation, others have removable liners). More athletically-oriented boots feel less clumsy to walk in, and are a good bet for day trips and warmer temperatures.