Keep Warm This Winter With The 10 Best Thermal Underwear

You may have heard at one point or another that winter is coming. And as much as we despise those colder temperatures, the frigid season is just as inevitable as Thanos, so it only makes sense to go ahead start preparing for it now. This is precisely where a handy set of thermal underwear can be of great use. Meant to layer under your existing clothing, thermal underwear adds another bit of warmth to your body, while also actively moving sweat away from your body to keep you from overheating. Whether it’s skiing down a slope, communing to work on a particularly harsh day or wearing them to keep warm on an overnight camping trip, thermal underwear is your not-so-secret weapon against the elements. Below, we’ve rounded up ten of the best thermals on the market to ensure you’ll stay warm—no matter what.

1. Patagonia Capilene Thermal Underwear

BEST OVERALL

Hikers will tell you that Patagonia’s Capilene underwear is some of the best thermal underwear around—and they’d be absolutely right. The Polartrec material makes for a lightweight, next-to-skin softness that’s incredibly comfortable to wear, regardless of activity; the odor control actively fights against and protects from getting too stinky. Perhaps best of all, they’re Fair Trade certified, so they’re ethically made at every single step. Each element of the thermal has been thoughtfully constructed and designed to ensure the best fit and feel possible—and once you’ve got them, you’ll be hard pressed to go back to anything else.

2. Duofold Thermal Underwear

BEST VALUE

At a great entry level price, this set of thermal underwear from Duofold is a solid option for those who want to test and see if long underwear is for them. Made by Champion, it’s rough and tough enough to handle most cold climates by combining two different fabrics into a material that feels like one. Luxury and comfort at an affordable price? Count us in.

3. Nike Training Long Underwear

BEST FOR WORKING OUT

If you’re the kind of person that wants a good workout thermal underwear, this particular version of Nike’s athletic long underwear is fantastic option. Thin and lightweight without feeling like you’ll rip them apart, they do a great job of replacing a standard compression short while hugging and supporting your legs. They’ll also do a fantastic job of wicking away moisture to keep you cool, even when you’re hot, so don’t worry about getting too warm while you’re hitting some HIIT training on the treadmill or at a workout class.

4. Lululemon Surge Thermal Underwear

BEST SPLURGE 

There’s a reason why Lululemon’s thermal underwear are beloved by so many: they’re some of the most comfortable and supportive pieces of clothing around. Crafted with Nulux, this thermal underwear is quick-drying, sweat-wicking, and lightweight. Tossing them under a pair of jeans or pants will make it feel like there’s almost nothing there. Plus, if you rock them for running outside, the rich blue will pop nicely with whatever else you’re wearing.

5. Under Armour Coldgear 4.0 Thermal Underwear

BEST FOR FREEZING COLD

The 4.0 in Under Armour’s numbering system helps to delineate the warmth of their various offerings, with 2.0 being the coolest and 4.0 being the warmest; so this particular pair will help you prepare for those really awful, cold conditions. The grid structure of the thermal underwear helps trap and retain heat, while keeping any sweat off of you to keep you cool and comfortable. That heat retention comes in a pair that’s still slim enough to layer without bulk, making them essential on days when you have to be outside for long period of time (i.e., skiing or shoveling snow).

6. REI Co-op Lightweight Thermal Underwear

BEST LIGHTWEIGHT

More than just a retailer for lots of other outdoor products, REI has their own in-house line that produces plenty of quality products. These lightweight thermal underwear bottoms are great to layer under pants that are already constructed from a dense material (i.e., wool, corduroy, etc) or in cases where you want just a little bit of warmth. You’ll still get the same great sweat-wicking and comfort you’d expect for other thermals, but in a lightweight and wallet-friendly package.

7. Columbia Thermal Underwear

BEST MIDWEIGHT

Much like Patagonia, Columbia has been a beloved outdoors mainstay for quite some time, carefully crafting fantastic technical staples. Columbia’s thermal underwear works by using their proprietary Omni-Heat tech; a series of heat-reflecting dots line the pant to direct warmth back at you, while actively moving sweat away from your body. At a midweight level, they’re also capable of handling the majority of cold conditions.

8. Terramar Military Fleece Thermal Underwear

BEST FLEECE OPTION

If you want a pair of thermal underwear that’s really, really going to keep you warm, we’d recommend this fleece (!) lined version from Terramar. While it’s not as great as other options when it comes to regulating body temperatures, that trade-off comes at the cost of providing extreme warmth in the most dire of situations (hence why it was originally created with military personnel in mind). The exterior is lined with a smooth face in order to make sure it doesn’t move around too much when placed underneath a pair of pants.

9. Odlo Thermal Underwear

MOST COLORFUL

Odlo’s thermal underwear boasts a vibrant electric blue gradient that will be fun to wear under gym clothes or just walking around casually at home. All the standard sweat-wicking and comfort features are present here, but there’s a little design detail that we love: the back of the knee has a slightly perforated mesh that allows for great breathability in an area that can get very sweaty.

10. LL Bean Thermal Underwear

MOST COMFORTABLE

LL Bean’s long underwear comes in a super comfortable merino wool that will feel fantastic whenever you put them on. That merino wool also ensures that they’re 100% itch free, so feel free to wear them all day long without concern. Plus, with great moisture-wicking provided by the natural wool fibers, you may actually want to just keep them on from the moment you walk out the door until well after you come back home.

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