Here’s why thermal clothing is essential for staying active during the winter.
Even if you’ve got all the essential cold weather pieces — a nice winter coat, thick sweaters, some trusty winter boots — you might be underprepared for particularly frigid weather.
Layering is critical, but throwing on jacket after jacket isn’t always the best solution. If you’re going to be heading out in bone-chilling weather, you need to make sure that your body temperature stays where it should.
You also need to be prepared for any unexpected changes. For example, if the sun comes out and hits you with some toasty UV rays, you don’t want to be wearing so much that you overheat.
In short, you need clothing that helps regulate your temperature. The human body does this naturally through a process called thermoregulation, but extremely cold temperatures can cause the body to lose more heat than it can produce, which can lead to hypothermia.
That’s why thermal clothing is so important. Thermal clothes are designed to trap body heat while wicking away sweat so that you warm up and cool down when you need to. The idea is to prevent the body from getting too hot or too cold.
Incorporating thermal clothing into your outfit is simple, but there are a few foundational concepts you need to know before you run out and buy any undershirts.
How Thermal Clothing Works
Winter layering involves three types of layers: base, mid, and outer. Each layer has a specific function:
Base layer: This is the layer that goes on first, meaning that it touches your skin the most. The role of the base layer is mainly to wick sweat away from your skin to prevent you from getting cold and/or wet, but it can also trap body heat. Finally, a base layer should dry out quickly for the rare instances when you get soaked.
Mid layer: This layer provides insulation and helps you retain body heat. As obvious as it sounds, you need both base and outer layers to have a mid layer (otherwise you just have a base and/or outer layer). This layer is often a fleece or puffer vest or jacket.
Outer layer: This final layer protects you from the elements, including rain, snow, wind, ice, and hail. This layer is often a hard shell jacket, soft shell jacket, or insulated jacket.
As its name suggests, thermal clothing is designed to be a base layer that captures and retains body heat. Typically, thermal clothing is made from either Merino wool or a synthetic fabric like polyester or nylon.
Like base layer clothing in general, thermal clothing is often skintight but flexible. If you rely on thick outer layers to stay warm, your movement will be restricted, and you can easily sweat up a storm.
Thermal clothing, on the other hand, allows for optimal freedom of movement so you don’t overheat when moving.
Thermal clothing is often recommended for the winter months for good reason, but you can also take advantage of it during spring and fall.
Thermal clothing is thin enough to layer under your regular base outfit (usually a T-shirt and pants), making it perhaps the most versatile layer.
The Best Thermal Clothing for Men
Since thermals are worn as part of the base layer, they fall into two major categories: tops and bottoms. Of course, there are various types of garments in each category, so it can take a bit of hunting to find the right pieces for you (especially if you’re new to thermal wear).
I’ve made it easier for you by scouring the internet for some of the best thermal clothing items you can buy right now. Whether you need a casual set of thermals or high-performance activewear, you’ll find something here to meet your temperature regulation needs.
The Best Thermal Tops for Men
There are a few different types of thermal shirts to choose from. You can go with a simple undershirt-style base layer, traditional crew neck tee, or even a waffle-knit henley. You can get away with thicker pieces for general everyday wear, but you’ll probably want something thinner for outdoor activities.
Here are some of the best thermal tops for guys:
Buck Mason Vintage Thermal Surplus Tee
If you’re after a more casual layer that provides a boost of warmth during the colder seasons, look no further than the Vintage Thermal Surplus Tee from Buck Mason.
This retro-style tee is made from a midweight 250 GSM French rib cotton and features a waffle-knit face and a smooth jersey back for maximum comfort. The classic fit means it will drape just the right amount on most guys.
While this tee isn’t ideal for intense activities, it’s a great way to get some extra warmth out of your cold weather outfits.
Smartwool Classic Thermal Merino Base Layer Crew
Need a thermal shirt that will keep you toasty on mountains and slopes alike? The Classic Thermal Merino Base Layer Crew from Smartwool has your back.
Made from 100% Merino wool, this base layer is constructed to effectively regulate body temperature while also optimizing mobility and minimizing chafing. This is a shirt that’s designed for extreme movement and activity, but it can pull double duty as a daily layer.
L.L. Bean Signature Waffle Crew
The Signature Waffle Crew ticks all the boxes that an everyday thermal shirt should: it’s made from breathable waffle-knit cotton, has a slim fit for easy layering, and features a timeless design that’ll go with just about any outfit.
This is the thermal shirt for guys who don’t want to look like they’re wearing thermal clothing. On the surface, it looks like a regular long-sleeve crew neck, but it goes the extra mile to keep you warm.
L.L. Bean Lightweight Crew Base Layer
As you might expect, L.L. Bean also makes some more performance-oriented thermal clothing, so if that’s what you’re after, consider the Lightweight Crew Base Layer.
This fitted crew neck is made from moisture-wicking polyester and treated with an anti-microbial finish to keep odor at bay. It’s also pretty inexpensive as far as thermal clothing goes, so if you’re after a budget base layer, this could be the one.
Patagonia Men’s Capilene® Midweight Crew
Of course, when anything involving outdoor clothing comes up, Patagonia has to get a mention. The brand’s Capilene Midweight Crew is an all-around fantastic option for a base layer that balances thermoregulation and performance.
This shirt is made from 100% recycled polyester and features raglan sleeve construction and underarm gussets for uninhibited movement. It’s also Fair Trade Certified™, which is rare for thermal clothing and serves as a testament to Patagonia’s vision.
The Best Thermal Underwear for Men
Of course, you can’t complete a full set of thermal clothing without underwear. But these aren’t your grandpa’s long johns — these are versatile underwear options that can help prevent sweating where it matters most.
Smartwool Classic Thermal Merino Base Layer Bottom
The Classic Thermal Merino Base Layer Bottom is another heavy hitter from Smartwool that features 100% Merino wool construction and several practical features that make this option stand out.
You get a comfortable interlock knit, a wool-covered elastic waistband, and a traditional fly. If you’re a regular runner, hiker, skier, or other outdoor adventurer, you should seriously consider picking up a pair.
icebreaker Merino 260 Tech Thermal Leggings With Fly
If you’re after high-performance wool underwear, New Zealand brand icebreaker has you covered with its Merino 260 Tech Thermal Leggings With Fly
These 100% Merino midweight leggings feature a mobility gusset, contoured pouch, and fly for a hassle-free experience. What’s more, the wool is non-mulesed and painstakingly chosen to adhere to icebreaker’s high standards.
Mack Weldon WARMKNIT Long Underwear
While wool reigns supreme in the world of thermal clothing, there are benefits to other fabrics, and that’s something the WARMKNIT Long Underwear highlights.
These bottoms are made from a combination of modal, polyester, wool, and spandex designed to offer softness, warmth, and flexibility. The no-roll waistband and ankle cuffs are nice practical touches that make this underwear a good bang-for-your-buck choice.
Carhartt Base Force® Midweight Classic Bottom
Carhartt doesn’t just make hardwearing jackets and pants — the brand also offers some durable base layers. The Base Force® Midweight Classic Bottom is an affordable thermal underwear option that packs a punch.
These 4oz polyester leggings are moisture wicking, stretchy, and comfortable. The Force FastDry® technology wicks sweat while the Rugged Flex® tech ensures that the fabric moves with you. At less than $50 a pair, it’s hard to go wrong.
Patagonia Men’s Capilene® Midweight Bottoms
If you’ve already gotten the Capilene top from Patagonia, you might as well spring for the matching (and identically priced) bottoms.
The Capilene® Midweight Bottoms are made from the same recycled polyester and feature similar construction, so if you get the tops and bottoms, you can be sure that the wearing experience will be the same.
Thermal Clothing FAQ
Need some quick answers about thermal clothing for guys? Here you go.
What is thermal clothing?
Thermal clothing is any clothing worn as a base layer that works to wick moisture from the skin.
What is the best brand of thermals?
The best brand of thermal clothing will depend on your needs. Some thermal clothing is made for general use, but some is designed specifically for intense outdoor activity.
How do thermals keep you warm?
Thermal clothing keeps you warm by wicking sweat away from the skin and preventing you from getting cold. Thermal clothing also works to retain your natural body heat.
Is thermal a brand?
Thermal isn’t a brand but a descriptor of what the clothing does.
Conclusion: Stay Warm With Thermal Clothing
Thermal clothing is a must have for anyone who participates in outdoor activities during chilly weather. However, it’s also a versatile way for guys to stay warm on a daily basis.
Of course, getting the right outer layers is just as important, but for maximum warmth, you’ll want to get some good thermal clothing.
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