Updated on October 12, 2020

As the temperature begins to drop, some people opt to retreat indoors to the comfort of a climate controlled environment. For those that dare to brave the cold and wind that often accompany activities like skiing and snowboarding, snowshoeing, and winter hiking and climbing, layering is essential. Selecting the right base layer can be as important as choosing the right sock for those brand new boots. A base layer will be the first line of defense that your body will have in regulating your core temperature and helping to transfer moisture away from the body during active pursuits. With so many manufacturers and fabric options to choose from, the task of selecting the best base layer can feel like an overwhelming endeavor.

Don’t sweat it! Here at The Adventure Junkies, we pride ourselves in helping you choose the best gear for your upcoming cooler weather adventure. In this guide, we’ll help you pick the best base layer so you can stay warm and insulated on your next foray into the great outdoors.

For more of our top hiking apparel recommendations, check out these popular articles:

Base Layers for Women | Wool Base Layers


Quick Answer - The Best Base Layers for Hiking

  1. Smartwool Merino 150 Bottoms
  2. REI Co-op Merino Midweight Bottoms
  3. Icebreaker 200 Oasis Leggings
  4. Patagonia Capilene Air Bottoms
  5. Smartwool Merino 150 Crew Top
  6. REI Co-op Merino Midweight Crew Top
  7. Icebreaker 200 Oasis Crew Top
  8. Patagonia Capilene Thermal Zip Neck


Comparison Table - Best Base Layers for Cold Weather Hiking

Smartwool Merino 150 BottomsBottoms With Fly OpeningLightweight87% Merino Wool / 13% Nylon$$4.8
REI Co-op Merino Midweight BottomsBottoms With Fly OpeningMidweight100% Merino Wool$$4.7
Icebreaker 200 Oasis LeggingsLeggings With Fly OpeningMidweight100% Merino Wool$$4.9
Patagonia Capilene Air BottomsBottoms Without Fly OpeningMidweight51% Merino Wool / 49% Recycled Polyester$$$$4.8
Smartwool Merino 150 Crew TopLong Sleeve Crew TopLightweight87% Merino Wool/13% Nylon$$4.8
REI Co-op Merino Midweight Crew TopLong Sleeve Crew TopMidweightMerino Wool$$4.7
Icebreaker 200 Oasis Crew TopLong Sleeve Crew TopMidweightMerino Wool$$4.9
Patagonia Capilene Thermal Zip NeckLong Sleeve Quarter Zip TopHeavyweight92% Recycled Polyester$$4.8
Want to learn more about a technical term? Check out our Features Explained section below.

Need buying advice? Take a look at these Things to Consider.

Reviews - Best Cold Weather Hiking Base Layers

Smartwool Merino 150 Bottoms

  • Insulation: Lightweight
  • Material: 87% Merino Wool / 13% Nylon
  • Style: Bottoms With Fly Opening
  • Moisture Wicking: Yes
  • Smooth Seams Minimize Chafing
  • Slim Fit
  • Fully Functional Fly


For over twenty-five years, Smartwool has been creating high quality products utilizing merino wool. The American based company was founded in Steamboat Springs, Colorado and was acquired by the VF Corporation (the same parent company that owns The North Face as well as other notable brands) in 2011. 

This lightweight, merino wool bottom layer is ideal for active pursuits in which breathability and the regulation of body temperature are paramount to the activities ahead. The wool’s natural properties help it to resist odors even when worn day after day. The wool is combined with nylon to create a more durable product while maintaining all of the superb properties of merino wool.

REI Co-op Merino Midweight Bottoms

  • Insulation: Midweight
  • Material: 100% Merino Wool
  • Style: Bottoms With Fly Opening
  • Moisture Wicking: Yes
  • Flat Seams Help Prevent Chafing
  • Wide Elastic Waistband For Comfort Under Layers
  • Gusseted Crotch For Full Range Of Movement


REI was founded in 1938 as a co-operative to help others acquire quality climbing gear at reasonable prices. Over eighty years later, the co-op operates over 150 stores as well as a thriving online business. In addition to selling quality gear from respected manufacturers, the brand also designs and creates their own line of tents, backpacks, sleeping bags, and apparel. 

This midweight base layer is made from 100% merino wool and is adept at providing the ideal blend of regulating body temperature and wicking away moisture from the body. These warm and cozy pants are perfect for wearing underneath your outer layers when you get a hankering for exploring the wilderness in the winter.

Icebreaker 200 Oasis Leggings

  • Insulation: Midweight
  • Material: 100% Merino Wool
  • Style: Leggings With Fly Opening
  • Moisture Wicking: Yes
  • Slim Fit
  • Contoured Pouch With Functioning Fly
  • Gusseted Construction Provides Unrestricted Movement


Another VF Corporation acquisition, Icebreaker was founded in 1995 in New Zealand, the epicenter of merino wool production. Its founder, Jeremy Moon, had a chance meeting with a sheep farmer over twenty years ago and the rest is history. Today, Icebreaker is one of the most respected brands in the merino wool market.

These midweight leggings offer a slim fit which is how a base layer works in close proximity to the skin. The gusseted construction offers unrestricted movement for a day full of activities without limiting mobility. The features of merino wool are evident in the Icebreaker 200 Oasis as it insulates, breathes efficiently, and repels odors for perpetual comfort on the trail or slopes.

Patagonia Capilene Air Bottoms

  • Insulation: Midweight
  • Material: 51% Merino Wool / 49% Recycled Polyester
  • Style: Bottoms Without Fly Opening
  • Moisture Wicking: Yes
  • Brushed Elastic Waistband For Extra Softness Against Skin
  • New Zealand Merino Wool Paired With Brand’s Capilene Recycled Polyester Means These Bottoms Are Both Very Warm And Very Comfortable
  • Double Layer On Front Crotch Provides Additional Support


Patagonia is renowned for its creation of premium products utilizing proprietary fabrics as well as existing textiles and treatment methods. The brand is also known for its commitment to environmental standards and protection. It utilizes recycled products when possible and is constantly seeking to make its products from recycled materials as well as recyclable on the backend. 

The Capilene Air base layer bottoms are no exception. This hybrid base layer is created from New Zealand merino wool along with recycled polyester. This unique blend creates a product that is extremely durable (hence the polyester) while utilizing the natural properties of the wool to create the perfect base layer combination.

Smartwool Merino 150 Crew Top

  • Insulation: Lightweight
  • Material: 87% Merino Wool/13% Nylon
  • Style: Long Sleeve Crew Top
  • Moisture Wicking: Yes
  • Raglan Sleeves (No Shoulder Seam And Extra Space For Movement In The Underarms)
  • Flatlock Seam Minimizes Chafing
  • Nylon Increases Durability Of The Merino Wool


Paired with the bottoms by the same name, the pair will blanket you in extreme comfort and protection from neck to ankle. And just like bottoms, the top is created by spinning the merino wool around a nylon core to create a durable and lightweight layer that places the soft wool next to your skin where it prevails at keeping you insulated while wicking moisture away from the body. The raglan sleeves ensure that there’s no seam along the shoulder and that extra room exists in the underarms for freedom of movement. The lack of a seam along the shoulder is ideal when wearing a pack, so you won’t have uncomfortable stitching digging into your neck and shoulders while you hike.

REI Co-op Merino Midweight Crew Top

  • Insulation: Midweight
  • Material: Merino Wool
  • Style: Long Sleeve Crew Top
  • Moisture Wicking: Yes
  • Flat Seams Help Eliminate Chafing
  • Gusseted Underarm For Increased Mobility
  • Droptail Hem (Longer In The Back) Aids In Keeping The Top Tucked In


REI has excelled at creating a niche for its products where they constantly rank right along the same brands the co-op sells in its stores and online. And just like the merino midweight bottoms from above, this long-sleeve crew top is created using ultra fine merino wool that offers a soft and comfortable feel while naturally resisting odors after days (and perhaps weeks) of nonstop use. The warmth of the midweight fabric will envelope the body while wicking away the sweat during activity. For active pursuits, the drop tail hem design features a longer back section to insure the top remains tucked in as you move and bend on the trail or slope.

Icebreaker 200 Oasis Crew Top

  • Insulation: Midweight
  • Material: Merino Wool
  • Style: Long Sleeve Crew Top
  • Moisture Wicking: Yes
  • Gusseted Underarms For Full Range Of Movement
  • Droptail Hem To Keep Shirt Tucked In While You Move
  • Offset Shoulder Seams To Prevent Stitching From Digging Into Your Shoulders While Wearing A Pack


Born in a country where adventure is a way of life, Icebreaker was founded in 1995 after a chance meeting with a sheep farmer who inspired Jeremy Moon to seek out a new approach to natural fibers and return wool to the top of the base layer game. The brand uses a sustainable approach by only using wool that is certified to the RWS (Responsible Wool Standard). The 200 Oasis crew neck features a drop tail hem for added coverage on your backside so that the top doesn’t come untucked when bending over to unbuckle your bindings or tie your boots thus allowing cold air to invade. This top is a great base layer for all your snowy adventures, whether that’s cross country skiing, snowshoeing, or shredding the slopes in the backcountry with all your adventure junkie friends.

Patagonia Capilene Thermal Zip Neck

  • Insulation: Heavyweight
  • Material: 92% Recycled Polyester
  • Style: Long Sleeve Quarter Zip Top
  • Moisture Wicking: Yes
  • Elastic Thumbholes To Keep Sleeves In Place
  • Front Zipper For Venting
  • Environmentally Friendly And Bluesign Approved


Founded in 1973 by Yvon Chouinard, Patagonia has become one of the most recognized names in outdoor and lifestyle apparel in addition to its ongoing commitment to environmental causes and sustainability. Unlike the Patagonia bottoms above that are a hybrid of polyester and merino wool, this heavyweight top is made entirely of polyester. Remaining true to its environmental standards, this thermal top is bluesign approved which means that it meets the international requirements for sustainable production of fabrics. This is also the only heavyweight product in this guide and is ideal for extremely cold weather when motion is limited. The zip-neck provides the option to vent as needed.





There are a multitude of options to choose from in the baselayer market. For this particular guide, we’re only going to concentrate on the top three: Merino Wool, Synthetic, and Hybrid (blend of merino and synthetic). Choosing the best base layer can be a matter of preference as well as preferred choice of material.

Merino Wool

This is not the itchy wool your parents and grandparents wore. Merino wool is the only natural fiber in this guide and its natural properties make it ideal for warmth, odor control, and wicking properties. The fibers are thinner and softer than traditional wool. Wool tends to keep you warm even when it gets wet and naturally repels odors so you don’t have to worry about stinking up a wool base layer even if you wear it for weeks on-end during a thru-hike or multi-day ski trip.


Until Merino came on the scene, synthetic base layers ruled the roost. Polyester is still preferred by many and with exception to odor control, it excels in the areas of durability, warmth and breathability.


Hybrid base layers possess the best of both worlds. Blended products incorporate the best properties of Merino wool and polyester. However, this option can also be one of the more expensive options.



There are 3 main categories of insulation: lightweight, midweight, and heavyweight. Some manufacturers may label the insulation levels differently, but they typically fall into one of those categories.


This is the thinnest and perhaps the most ideal for active pursuits on moderately cold days. Lightweight layers made from Merino wool can be less durable than polyester products as the thinner wool products tend to wear faster and may only last a few seasons while their synthetic counterparts can last substantially longer.


As the name implies, this insulation weight is middle of the road. It’s a perfect base layer for active endeavors on cold days. It can also be worn as a standalone layer on cooler days.


This is the paramount choice for relatively sedentary activities. The extra thick base layer can be overkill for activities like cross-country skiing, hiking, and even downhill skiing except on perhaps the coldest days.



To perform optimally, base layers should fit relatively snugly and perform like a second skin. The closer the material is to your skin, the better it can perform its intended purposes of moving moisture away from your body. Though, at the end of the day, it’s important to choose a product based on your particular needs and preferences for fit.



Premium products often carry a premium price. While relatively moderately priced, base layers can be as essential as mid and outer layers. This will be the first layer of defense against the elements and it will be next to your skin. Therefore, it’s important to choose a layer based on its properties, fit, and comfort. Saving money won’t pay dividends if you end up shivering and cold sitting on a chair lift.



Layering is the key to thriving in active pursuits during cooler weather. Choosing a quality base layer is as essential to your overall comfort as building a proper foundation before building a house. This sets the stage for the performance of all subsequent layers.





Consumers seeking textile products that meet stringent environmental standards can rest assured when finding the “bluesign” designation label on a product. To receive this designation, a product must conform to these standards from the beginning to the end of the production process. Patagonia was the first brand member of Bluesign Technologies.


Wicking is a fabric’s ability to draw moisture away from the body. Unlike cotton which absorbs moisture and makes it less than ideal for an insulating layer, natural fibers like Merino wool and synthetic fabrics like polyester are excellent moisture-wicking fabrics.


Tops with a crew neck have a round neckline with no collar.


As the name implies, tops featuring a half-zip (sometimes only feature a quarter-zip) allows the user the option to unzip to allow for further ventilation and it makes removing over a helmet or other gear easier than a crew neck. Also, the higher neckline provides more warmth as the neck can often be an exposed area.


A raglan sleeve consists of one continuous piece of fabric that extends from the collar to the underarm. There is no shoulder seam in this style of shirt or jacket, which makes it more comfortable while wearing a pack because you won’t have uncomfortable seams digging into your shoulders while you hike.


Seams are butted together and joined with stitching to provide a nearly seamless design to avoid overlapping of layers.


When the back of the shirt or top is longer in the back than the front. This assists in helping to keep the shirt tucked in during active pursuits when regular hemmed products might come untucked.


In apparel design, a gusset is typically a triangular piece of fabric (can also be other shapes as well) that when sewn into a seam can increase mobility. These are often added to regions like the underarm, crotch, and other areas that might benefit from extra area in the product.


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