Best Thermal Underwear: Take Control over Winter Weather

Best Thermal Underwear
Jerry Mueller
Written by Jerry Mueller

It can be difficult to stay warm during the holiday season, especially when there’s the risk of snow storms. You could choose to stay inside under your blankets and in front of the fireplace, but soon you’ll run out of food, and you’ll need to shovel that walk of yours.

Or you’re someone who enjoys winter sports, but hates how soggy and cold their clothing feels against their skin. These problems could be done away with by investing in a pair of the best thermal underwear you can find on the market.

That may be difficult to do, if you don’t know what you should be looking for.  That’s why it’s important that you read through this article so that you won’t waste time in the clothing store, wondering which one you should get.

Thermal underwear

Some of the best long underwear come in pairs – a matching top and bottom – but there are also separates so you can mix and match as you like to find the right comfort level for you. Now let’s get started on the various features you should keep an eye out for.

Features to Look for

Besides the obvious feature of keeping your body warm, there are some additional features you should keep in mind when looking for thermal underwear:

  • Stretch: stiff fabric won’t feel good against your skin, and not everyone is built the same way. A little bit of stretch allows the fabric to mold better to your skin so that it can provide more warmth to your body.
  • Bacteria resistance: especially if you’re camping and can’t shower or bathe every day, this feature is imperative. The growth of bacteria on the fabric from repeated wearings will lead to your thermals smelling bad, as well as making you more prone to skin infections.
  • Loft: this is similar to thread count on your bed sheets. Low-density weaves will allow your fabric to keep its shape and still trap the warm air against your skin, while still having some flexibility so you won’t feel restricted in your movements.
  • Moisture wicking: even in winter, you still sweat if you overheat, and that can make you feel colder even when you’re bundled up. Choose fabrics that are moisture wicking that will remove perspiration from your skin so that you can stay warm and dry.

Fabric Types

Although the main purpose of thermal underwear is to keep you warm, there are a variety of fabrics that achieve this in different ways. Some of these may have more stretch than others, while some underwear aren’t machine washable. Which one you choose is simply a matter of preference.

  • Synthetic: synthetic material such as polyester, nylon, rayon, and spandex are easy for manufacturers to make, so they’re going to be a bit more affordable for budget shoppers.
    They dry much faster than other fabrics, which makes them great for wet conditions such as heavy, wet snow. They’ll also wick away moisture more effectively from the body so that you stay dry and warm.
    Synthetic thermal underwear are some of the lightest out there, and are resistant to abrasions and wrinkles. They’re also super easy to care for: just throw them in the wash and the dryer, and they’re ready to wear in no time.
    One downside to synthetic material, however, is that they can’t be worn repeatedly on multiple outings without washing, as odours will build up easily. Another is that synthetic material is very vulnerable to staining, so wash them inside out.
  • Merino Wool: offers a lot more warmth than synthetic materials of the same thickness, but is still comfortable even on warm days. It works best in somewhat cool conditions, but it can be worn for a majority of outdoor activities.
    Because of the ultra-fine fibers in Merino wool, it isn’t as itchy as regular wool and actually feels great against the skin. It traps warm air against the skin, and absorbs any moisture or sweat that may be trapped underneath to keep you dry.
    It can be worn repeatedly without any buildup of odours, as it is naturally antibacterial. However, it doesn’t dry as quickly as synthetic materials, and can be a bit more expensive. Wool should be washed in cold water and placed flat on a towel to dry.
  • Silk: this fabric works beset in moderate cool weather, as well as with snow sports and other activities. Look for silk that has been treated, as this means that it has been improved to wick moisture away from the skin. It does do this a bit more slowly than synthetics, but it does have a luxurious feel against the skin without adding any bulk.
    This fabric is delicate, however, and must be cleaned after every use in order to maintain its shape and look. Hand washing is recommended in order to prevent shrinking, and silk is extremely vulnerable to sunlight and abrasion. If you don’t want to hand wash, the delicates cycle on your washing machine will get the job done.
  • Cotton: this may not be the best fabric to go with, as it retains perspiration very easily, leaving you clammy and chilled. Cotton, however, is one of the cheapest fabrics, which makes it an easy material to use in thermal underwear.
    If buying cotton thermals, look for products that are a blend with any of the other three materials listed above. Cotton needs to be washed in cold water in order to prevent shrinking. To dry quickly, place flat on a towel; hanging can lead to stretching and losing its shape.

Many manufacturers choose to make thermal underwear from a combination of these fabrics in order to increase the benefits of the product and minimize the drawbacks.

Fabric Weight

Clothing shouldn’t be heavy, but this isn’t what is being referred to when talking about thermal underwear. It’s the ability of the fabric to handle certain weather conditions and temperatures so that you’re always getting the optimal amount of protection.

Fabric Weight

These are the guidelines for determining what fabric weight you should get for your thermal underwear:

  • Ultra lightweight: also known as microweight, this is perfect for mild and cool conditions.
  • Lightweight: works in cool to moderately cold conditions.
  • Midweight: works well for moderately cold to cold conditions.
  • Heavyweight: great in cold to frigid conditions.

If you’re someone that gets cold really easily, then it would be best to invest in heavier fabric weights than the temperature recommendation stated above. However, keep in mind that if it does warm up unexpectedly, the heavier thermals are going to feel too warm to be comfortable.


This is more than just the size of the thermal underwear you choose. This is referring to how they are structured to fit against your body so that they can be comfortable in a variety of situations. The best fit should provide support but not constrict the limbs, making it difficult for you to move or will trap hot air pockets to add to your discomfort.

For warmer conditions, look for underwear that is loose. This way, your skin can still breathe. In colder conditions, look for underwear that is snug or advertised as “athletic fit.”

Colors and Styles

When it comes to thermal underwear, there are only two styles to really pick from: one-piece and two-piece. The one-piece thermal underwear suit can be a bit more difficult to get on, and may not be as form fitting as a two-piece, since not everyone’s body is made exactly the same.

This can lead to bunching up in areas that add discomfort and cause hot pockets of air to get trapped. There’s also the problem of trying to get this off when you really need to go to the bathroom.

With a two-piece, however, you can choose the various sizes to fit your body accordingly, so that you’re getting an even distribution of heat throughout. It’s easier to get on, just like a pair of leggings or a long sleeve shirt, and is less likely to bunch up in uncomfortable places.

Colors and Styles

In regards to colours, the most common ones are white, grey, light blue, black, and beige. It is possible to find a larger array of colours and patterns, depending on the various fabrics that are being used in the manufacturing of the thermals.

Polyester, spandex, cotton and silk tend to have the largest selection of colours to choose from, as it’s the fabric that is doing most of the work in trapping warmth. Other synthetics and wool tend to be in darker colours like blue and black so that they can be washed in cold water without the risk of shrinking or fading dye. There are some lighter colours, however, if you take the time to do some searching.

Now that you’re aware of what you should be looking for when it comes to thermal underwear, here are some of the top rated products on the market as a starting point for finding the product that is right for you.

Top Products of 2017

Duofold Women’s Mid Weight Wicking Thermal Shirt

Duofold Women's Mid Weight Wicking Thermal Shirt

Cost: $7.50 – $32.00

Material: 60% Cotton, 40% Polyester

Features: machine washable, double-layered, moisture control, flat lock seams, tag-free, available in six colours.

Description: This wicking Duofold Women’s Mid Weight Wicking Thermal Shirt is great for getting cozy this winter without overheating. It comes in a variety of alluring feminine colours, and the texture is so soft that it won’t chafe your skin.

That’s because the combination of polyester and cotton allows for a soft fabric with wicking capabilities.

The double layer helps to trap in warmth, but the breathable fabric will keep you cool enough so that you’re not sweating all over yourself. You’ll never have to worry about the chills of winter ever again with this lovely thermal shirt.

Duofold Men’s Heavyweight Double-Layer Thermal Shirt

Duofold Men's Heavyweight Double-Layer Thermal Shirt

Cost: $21.57 – $351.99

Material: 96% Polyester, 4% Spandex Bi-Polyester

Features: machine washable, double-layered, four-way stretch, moisture control, droptail hem, flat lock seams, tag free, anti-microbial for odor resistance.

Description: This Duofold Men’s Heavyweight Double-Layer Thermal Shirt is perfect for the winter season, as it will keep you warm and dry, even when it’s snowing heavily out.

It’s only available in one colour, but the buying options make it easy for you to stock up: you can buy one, two, three, five, or ten of these high-quality shirts in one go, so you can wear one every day of the week without having to wait to get your other pairs out of the laundry.

And you’ll never have to worry about smelling a little off if you wear these during rigorous activity. The fabric is anti-microbial, so it will kill the bacteria responsible for that underarm stink.

Terramar HOTTOTTIES 3.0 Ecolator CS Fleece Long Sleeve

Terramar HOTTOTTIES 3.0 Ecolator CS Fleece Long Sleeve

Cost: $76.55

Material: 95% micro polyester, 5% spandex

Features: ClimaSense treatment, wicks away moisture.

Description: This Terramar HOTTOTTIES 3.0 Ecolator CS Fleece Long Sleeve is extremely comfortable, you may not want to wear anything else. It may seem a bit pricey, but the ClimaSense treatment is definitely worth every penny.

It reacts to your body temperature and adjusts itself accordingly so that you’re always comfortable: too cold, and the shirt will warm up; too hot, and it will provide a cooling effect so that you’re not overheated while engaging in rigorous activities.

And in the off chance you do sweat a little bit, the moisture transport system will keep you dry so you won’t feel all icky under your thermal shirt. It has everything you could ever want in an undershirt for the winter season.

Polarmax Women’s Double Base Layer Pant

Polarmax Women's Double Base Layer Pant

Cost: $4.99 – $40.00

Material: 100% Acclimate dry Polyester

Features: flat seams, breathable, wicks away moisture, quick-drying, relaxed fit, available in two colors, double-layered, machine washable.

Description: Why ignore your legs when they could benefit from the warmth of Polarmax Women’s Double Base Layer Pant too? These soft and comfortable thermal pants are easy to wear under your clothing, and will keep you warm even when you’re skiing, snowboarding, hiking, climbing, or just shoveling your walk.

The breathable material won’t trap sweat, so you can stay cool without freezing. These are definitely a more affordable option than some of the other products in this list, which is great for those who are shopping on a budget.

Polarmax Unisex Youth Long Sleeve Crew

Polarmax Unisex Youth Long Sleeve Crew

Cost: $6.90 – $34.95

Material: 100% Acclimate dry Polyester

Features: available in four colors, flat seams, breathable, wicks away moisture, quick-drying, relaxed fit, double-layered, machine washable.

Description: Your kids shouldn’t be without protection from the harsh elements either. This long-sleeved thermal Polarmax Unisex Youth Long Sleeve Crew will keep them warm, minimizing their risk of hypothermia and getting sick during the holiday season.

This way, they can still go out and have fun in the snow without you having to worry about their health. There’s a wide range of sizes to choose from to fit your kid’s body type, so there’s no struggle with finding something that will fit.

Duofold Men’s Midweight Double-Layer Thermal Pant

Duofold Men's Midweight Double-Layer Thermal Pant

Cost: $15.94 – $34.99

Material: inside layer – 65% Cotton, 25% Merino Wool; outer layer – 10% Nylon

Features: available in two colours, machine washable, tag-free, flatlock seaming, double-layered.

Description: If you want plenty of warmth without the added weight of super bulky jackets, these Duofold Men’s Midweight Double-Layer Thermal Pant are the thermal leggings for you. The double-layered fabric is guaranteed to trap the heat you need to optimize your warmth, while still being breathable so that you won’t sweat.

The seams are flatlocked, so you won’t have to worry about chafing and discomfort while you wear these under your normal clothes. Beware that there may be some shrinking after it’s first wash, so you should exercise care in finding the right size that will fit you.

Instead, lay these on a flat towel to dry after washing so that they can retain their shape and won’t shrink as much.

Ibex Outdoor Clothing Women’s Woolies Crew Shirt

Ibex Outdoor Clothing Women's Woolies Crew Shirt

Cost: $49.95 – $105.00

Material: 100% Merino Wool

Features: tag free, flat lock seams, machine washable, available in ten colors, lightweight.

Description: Want your thermal Ibex Outdoor Clothing Women’s Woolies Crew Shirt to be fashionable? You’ll have a hard time picking from these wonderful colors that Ibex has available.

They’re colorful enough to be worn on their own without looking frumpy. And they won’t lose their shape, no matter how many washes you put them through, so they’ll last a very long time, allowing you stay warm season after season.


It’s important to stay warm during the winter season, or else you could be jeopardizing your health. Instead of layering up in bulky jackets so thick you can’t even fit through your door, consider investing in a few pairs of thermal shirts and/or leggings to keep you arm, and they’re discrete enough to fit under your normal clothing, so everyone will be wondering what your secret is.

Choose your Thermal underwear

Do you have a favorite pair of thermal underwear that we haven’t mentioned in this list? Please leave your recommendations and comments at the end of this article, as we’d love to hear from you.


Jerry Mueller

Jerry Mueller

Jerry ‘Boy Scout’ Mueller spends 99% of his time camping or teaching others how to live in the wild. He became an Eagle Scout which is the highest rank attainable in the Boy Scouting division when he was 17 and after that he still lives the scout life. Jerry always plans neatly every trip, takes leadership very seriously and if you listen to his tips and stories, you can learn tons of useful things.