How to Choose Base Layers for Cold Weather for 2021?

How you combine the best base layers for extreme cold weather along with all types of hiking clothing (jackets, pants, etc.) for casual hiking or cold?

In this post, you will learn how to combine all depending on weather conditions.

That is one of the best and most important lessons a hiker needs to know, next to safety: choosing the proper or warmest base layers depending on the weather conditions.

What are the Base Layers for Cold Weather?

You may have heard them as thermal clothing too.

A base layer for cold weather is what you wear when the weather gets cold, directly on your skin.

Most think that when the weather is such, they need to wear plenty and thick clothes.

That is not correct. A key ingredient in winter hiking is the “onion layers” layering system.

Base layers (thermal clothing) are made for such reasons.

They have plenty of properties depending on their materials, and their results change depending on how well you combine them with all other hiking clothing as you hike!

Apart from that, base layers can also be used in city walking when the weather is cold. They are not exclusively for hiking or/and mountaineering.

What are the Materials for Base Layers for Extreme Cold Weather?

Nowadays, as materials evolved, base layers are worn for non-hiking reasons too.

The reason why is they are elastic, light, and flexible to be a “winter t-shirt,” that keeps you warm and allows you not to wear many heavy clothes to get warm.

The most popular materials they are made with are Polyester, Poly-amid, Polypropylene, Wool, Merino Wool.

They slightly differ per season.

On top of the materials, the actual weaving of the materials plays an essential role in the efficiency, quality, and seasoning of the base layer.

To cut it short: Thick weaving is met to winter base layers and thus keeps the body temperature as steady as possible.

Thick weaving doesn’t mean that the base layer will end up being heavy. On the contrary, it will be light and thing.

In that way, you can choose the proper activity material.

For skiing or mountaineering, you must choose a breathable material, as the last thing you would like is to swim in your sweat. 

Base layers made from wool will keep body temperature at a reasonable level, even after getting wet.

Under the same logic, there are base layers that are not suitable for days with radical temperature changes, i.e., from very cold to hot. Such conditions may happen when you walk through a forest in winter and then rise to the bright sun without wind cooling you down.

There are some exceptions with base layers that perform well both in high and low temperatures. 

Here is a breakdown of different materials for base layers and their benefits.

Base Layer Synthetics

That is the most common type of long underwear. Why?

  • Super fast to dry
  • Durable
  • Inhibit odor retention (for multi-days trips bring more or have some tolerance)

Merino Wool for Base Layers for Cold Weather

Not the itchy type of wool. It is soft with fine fibers.

As a material, it is used as supplementary material with other fabrics (i.s. spandex). Why is it great? 

  • It wicks well (some moisture is retained in wool and gets a bit longer to dry) 
  • Is cooler (gets cooler when weather is warmer)
  • Durable, but up to some point (if you carry a heavy backpack it will wear through with time) 
  • Odor-free (Wool is highly odor resistant to bacteria that actually cause odors) 


Extraordinarily soft but not for severe conditions. Why?

  • Not so excellent wicking (when lots of sweating is involved)
  • Lightweight but not durable 
  • Keeps odors in 


This “technology” includes wool embedded with ceramic particles, and most claim that this material is top for the warmest base layer clothing.

Such clothing is for hot weather only, as ceramic will attract body heat and, at the same time, will dissipate it quickly, thus leaving you far more relaxed. 

How to Choose the Best Base Layers for Cold Weather?

In summary, there are three main factors to take into consideration.

Materials: Either synthetic or wool, it needs to keep the sweat off your skin. That is called “wicking.” 

Weight: You will meet three types of “weights.” These are Lightweight, Mid-weight, Heavyweight. The thicker, the warmer it gets. 

Fitting: Fabric has to be in direct contact with your skin to be efficient. You don’t want to feel it “tight,” but more like a snug fit.

How to Wear Base Layers for Hiking?

One of the most discussed topics between amateur hikers is how to combine clothing under different weather conditions.

Before moving to the analytic diagram for this, let’s state what “different weather conditions” really mean.

Hiking can happen in many different types of terrains under different (and changing) weather conditions.

For example, it can be sunny and cold, but then it can get colder as you walk through a forest, then it can become even stiffer as you get out of the woods to a hillside where the North cold wind blows, etc., or it can become warmer.

When you walk, you can meet all kinds of conditions.

What do you wear when things are like that? There you need the “onion layers” clothing.

Here is the table explaining how to do that. With mid-layer, we mean either a fleece or a loft jacket. With the outer layer, we mean a hardshell or softshell jacket.

Best Base Layers for Extreme Cold
How to wear clothes depending on the weather

How Base Layers for Cold Weather Actually Work? 

Here is a brief explanation.

There is a thin polyester layer in the inner part of the base layers.

That acts as an insulation layer.

Then the coating absorbs the moisture from the body and “pushes” it out. In that way, your skin remains dry.

The question here is: why to keep the skin dry?

The “elders” said that when you get sweaty and the surrounding temperature is low, then you will feel that external cold multiplied and on your skin.

That invites the risk of getting a cold, plus your energy will gradually decrease as your body will try to balance internal with external temperature. 

As this happens, you will also need to consume more energy (food), but that won’t equalize the effect of freezing further.

On top of that, the extra sweat is annoying by itself.

Due to their thicker weaving, base layers keep the temperature where it is meant to be and don’t allow it to “get out.”

So, you save yourself warmth by using your production of heat.

Moisture is expelled from your skin, leaving you with less odor and a lack of microbes that love moisture.

Base layers are meant to wear directly on your skin, without any other fabric between your skin and them.

Regarding the size, it must fit but not being too tight. It needs to be elastic enough so you can have all ranges of motion. 

What Types of Base Layers Exist? 

There are t-shirts, tops, bottoms, socks, and gloves, and you can choose as many as needed depending on the conditions.

The good thing is that they are light and compact, so they take very little space and weight in your backpack.

Thermal (Base Layer) Tops

Even if you don’t hike through icy terrains, you can replace some of your cotton long-sleeved shirts with base layer ones. 

There are many options, from base layers that look like a typical shirt to very technical ones suitable for extreme temperature conditions and turnarounds. 

The ones that “resemble” a typical t-shirt are the ones you can wear in the city too.

Crew Top Midweight Cold Weather Base Layer

Midweight Base Layer Crew Top

Fabric: Polyester (bluesign® approved)
Moisture Wicking: Yes
Quick Drying: Yes
Underwear Weight: Midweight

Patagonia Capilene Midweight Zip-Neck Top

How To Combine Base Layers & Hiking Clothes

Fabric: Recycled polyester/polyester
Moisture Wicking: Yes
Quick Drying: Yes
Underwear Weight: Midweight

Merino Wool Base Layer for Cold Weather Men’s Long-Sleeved

Best Base Layers for Extreme Cold Weather, Mountain Warehouse Merino Mens Baselayer Top

Fabric: 100% merino wool
Moisture Wicking: Yes
Quick Drying: Yes
Underwear Weight: Lightweight

Icebreaker Merino Oasis Crew Neck Shirt

How To Combine Base Layers & Hiking Clothes

Fabric: 100% merino wool
Moisture Wicking: Yes
Quick Drying: Yes
Underwear Weight: Lightweight

Base Layer Tights or Thermal Pants for Extreme Cold Weather?

These are suitable for very cold weather hiking but will also be useful when you stroll in the streets of a frigid (North) European city, where temperatures drop low.

We found a pair of base-layer bottoms to be a lifesaver on our trip to Moscow during New Year’s Eve.

Temperatures dropped to -20oC, and winter pants were not enough.

You can use women-specific tights as they are (without extra pants) for either hiking or running, and there are bottoms you can use as underpants.

See this post about women-specific hiking pants and leggings.

Men have their base layer underwear, too (short or long).

Apart from keeping your “privates” warm, they are elastic. During many hours of hiking, you don’t want sweaty cotton underpants.

In case your work involved spending too much time outside, they are perfect for that also.

Hot Chillys Women’s Micro-Elite Chamois Tight

How To Combine Base Layers & Hiking Clothes

Fabric: 89% polyester/ 11% lycra spandex
Moisture Wicking: Yes
Quick Drying: Yes
Underwear Weight: Midweight

Outdoor Research Men’s Alpine Onset Bottoms

How to Choose Base Layers for Cold Weather for 2021? 1

Fabric: 100% Merino Wool
Moisture Wicking: Yes
Quick Drying: Yes
Underwear Weight: Midweight

Thermal (Base Layer) Socks for Cold Weather

In the same logic, thermal socks are great if you want to keep your feet warm. They come in short and long (up to your knee).

Heatgear Tech Crew 3Pk Unisex Socks

How To Combine Base Layers & Hiking Clothes

Fabric: 97% Polyester, 3% Elastane
Moisture Wicking: Yes with Anti-odor technology


For special occasions, you can always add some extra gear to keep your head warm. Balaclavas are such gear. These cover most of your head and face, thus highly decreasing the loss of body heat. 

Base Layer for Cold Weather Clothing Maintenance

The same rule for all “technical” gear as this one, applies here. Follow the manufacturer’s instructions for washing, cleaning, and storage.

Such clothes are usually washed at 30oC and not in a laundry machine. 

Do not use softeners or “hard” detergents to decrease the life cycle of base layer clothing.

Such clothes usually dry very fast, and that is another reason outdoor activities enthusiasts prefer them. 

Want to learn more about hiking gear? Explore more posts from our hiking gear section, like Ultralight Backpacking Gear BasicsBest Trekking Poles for Men and WomenBest Hiking Leggings for WomenBest Hiking Gloves, and many more.

Share this post with your friends.

1 thought on “How to Choose Base Layers for Cold Weather for 2021?”

Leave a Comment