Winter Boot Basics: Insulation, Waterproofing & Staying Warm

Know your Sherpa from your sheepskin? Prep for frigid temperatures with this Pro Tips guide to winter boots and insulation.

The key to any good adventure might just be the right pair of winter boots.

From a muddy backcountry hike to a day on the slopes, your winter boots keep you in step as you move in harsh conditions ­– protected, warm and stable. So, when you’re prepping for your next outing, it’s important to know a thing or two about your outdoor footwear. Pro Tips is here to help you choose your next pair of insulated winter boots.



winter boot basics



The Upper: The soft, outermost portion of your boot. This component is made of such materials as leather, suede, rubber or synthetics.

Lining: Boot lining can be comprised of fleece, fur, sheepskin or synthetic materials. Many brands offer insulation that uses specialized fibers to trap and retain heat. And don’t forget about a waterproof liner. Removable boot linings let you customize your level of warmth as the conditions change. If your boot is wet at the end of your trek, you can simply remove the liner to allow it to dry faster.

Midsole: Molded materials, like EVA or polyurethane, provide support and shock absorption for comfort. Keep in mind: The thicker the midsole material, the more warmth provided, as your foot is farther from the ground.

Outsole: The all-important outsole is critical for trekking through snowy, muddy and wet terrain. Traditionally, boots feature rubber outsoles, and for good reason: Rubber is naturally waterproof and slip resistant.

When shopping for insulated winter boots, always refer to the thickness of the outsole. Many boots come with spikes or lugs for walking over rugged terrain. Other boots come with specialized tread patterns designed to increase slip resistance.

Toe Box: The toe box is a layer of protection that extends over your toes. Some toe boxes are covered with a layer of insulation for extra warmth. Work boots are often constructed with protective steel or composite materials, too.



To make sure your feet stay warm during the cold months of the year, you’ll want your boots to have an insulating material that helps trap the heat inside.

  • There are a variety of synthetic insulations designed to keep you warm. Most synthetics are made of microfibers designed to trap air molecules which can help keep warm air in your boots and cold air out. Different brands may have their own type of synthetic insulations, but all are often water resistant, quick drying, thermal and breathable.
  • Neoprene is a synthetic rubber that can be warm, lightweight and durable. Neoprene remains a popular material for diving wetsuits and work gloves.
  • Fleece is lightweight, yet thermal. It also wicks moisture to keep you dry and comfortable.
  • Shearling is a fine fleece produced naturally or artificially. Like traditional fleece, it’s soft and cozy but not well suited for extreme conditions.
  • Sheepskin lining is naturally soft textured and moisture wicking for performance in extreme temperatures. Plus, it’s plush enough to provide an extra layer of cushion in your footwear.
  • Sherpa is a man-made material that mimics the texture of shearling. This material is soft, warm and has the added benefit of being easy to clean. Sherpa also wicks moisture away and dries quickly.


When choosing your winter boots, you might see a number next to the name of the insulation. This number tells you the amount of the insulation used. Measured in grams, this number can range from 100g to more than 1000g. The higher the number, the warmer the boots should be.


Here’s a rundown of the levels of insulation and what you can typically expect:

  • 200 grams or less: Good for cool conditions or high activity levels.
  • 400 grams: Can be beneficial in bitter temperatures or moderate activity levels.
  • 600 grams: A solid choice to hold up against very cold temperatures.
  • 800 grams: Found in boots designed for bitter conditions with light activity levels.
  • 1000 grams or more: Best for extreme cold with minimal activity. Many hunting boots feature 1000g insulation or higher.



If you want your feet to be warm, keeping them dry should be a major priority. Boots can come with various designs that help your feet stay that way, water-free.

  • Many boots feature a waterproof membrane built into the design. This porous lining is made to help repel and block moisture while maintaining breathability.
  • Some boots can be treated to achieve waterproof conditions. Companies treat their footwear with different agents to help repel moisture, or you can treat them yourself at home. If your boots are untreated, check out this Pro Tips guide on how to waterproof your boots.
  • Rubber shells can help protect the lower portion of the boots. This shell can help your feet stay dry through snow and slush.

Ready to pick out your next pair? Start your search with our article on the best winter boots for men and women. And don’t forget about your hands! Check out this guide from Pro Tips on how to choose the best winter gloves for your activity.