No matter the season, it’s always a good idea to bring an extra jacket along when you’re heading outside. But as temps start to drop, dressing wisely is even more important (and we’re not just talking about finding the right puffer coat). An easy way to insulate yourself from the cold is by wearing some great base layers—a.k.a. thin, lightweight, long-sleeved shirts and tights that fit under the rest of your clothes.
That might not sound like enough to keep you warm, but these pieces are a great foundation for the rest of your layering. And when you’re bundled up properly, you can stay comfortable in cold or unpredictable conditions without sacrificing your range of movement. Here, we spoke to hiking and gear experts about the best base layers you can add to your winter wardrobe, plus how to suit up safely for your next chilly outing.
FAQs about base layers
What to look for when shopping for base layers
You can shop for base layers the same way you shop for other outdoor apparel, but keeping the following features in mind can help you streamline your search.
- Fit: Good base layers will fit close against your skin, Maggie Peikon, manager of communications at the American Hiking Society, tells SELF. They should feel snug, but not too tight. Keep in mind that some base layers are made to feel compressive, which might not be as comfortable (depending on your preferences).
- Materials: The best materials for base layers are Merino wool and synthetic fabrics like polyester, nylon, or rayon, since they’ll help you stay warm and prevent you from overheating, Mike Kreis, a sales and service specialist at REI, tells SELF. These materials wick moisture away and regulate your body temperature better than cotton, which actually holds onto moisture—and it’s much harder to stay warm when you’re damp, Peikon explains. She also suggests looking for fleece-lined base layers: Although they don’t have the same quick-drying properties as synthetic and wool pieces, they’re great when you want to feel extra warm and cozy.
How to properly layer clothing for cold weather
Ingrid Johnson, a product specialist at REI, previously gave SELF an excellent metaphor for layering: “Dress like the layers of an onion, where each garment moving outward gets slightly bigger so that you don’t limit range of motion or compress your circulation and end up colder.”
With that in mind, after you put on your base layers, you can add a mid layer like a fleece or a thin down jacket to add insulation and warmth—just make sure it’s easy to take off if you start to overheat, Peikon says. (Kreis points out that you don’t have to start your day with a mid layer if you think it’ll be too hot from the get go: “Remember, you can always leave a warmer mid-layer in the car or your pack.”)
The outer layer in your “onion” should protect you from the elements, like a wind- and water-resistant shell-style jacket, Peikon says. Check that it’s roomy enough to wear over your other layers comfortably—even though you’re bundled up, you should still be able to move.
Shop the best base layers
As much as we love an indoorsy day during the winter, you don’t have to cancel your outdoor plans just because it’s cold—not once you have some high-quality base layers, that is. We selected our top picks based on recommendations from SELF staffers and the experts we spoke to. Check them out below, then get psyched for your next cold weather excursion.
Best base layer tops
Smartwool Intraknit Active Base Layer Crew
Pros
- Temperature-regulating wool blend
- Odor-resistant
- Made with minimal seams
Cons
- Runs small, according to reviewers
Ventilated, stretchy, and designed to reduce chafing, Smartwool’s Intraknit Active Base Layer is perfect for exercising. Zappos reviewers love it for ice climbing and cross-country skiing, and it’s a favorite of SELF’s director of fitness and food too. Its vented panels are strategically placed for airflow where you need it most (raise your hand if your back gets obscenely sweaty during workouts), and its wool blend fabric is made to feel extra lightweight and soft against your skin.
Sizes: XS to XL | Materials: Merino wool, lyocell, polyester, elastane
Under Armour ColdGear Mock Long Sleeve
Pros
- Very stretchy
- Soft, warm lining
- $60 and under
Cons
- Compressive style may feel too tight for some
Our director of fitness food and senior commerce writer both swear by this toasty-warm mock-neck shirt from Under Armour—in fact, they’ve had theirs for years. “I’d have to sit out most of the fall climbing season without this shirt,” our writer says. “It’s snug—like, very, very snug—but still moves with me. I run cold, and I can pile several more layers on top of it without feeling restricted.”
The ColdGear Mock Neck Long Sleeve feels smooth and sleek on the outside, but soft and brushed on the inside. Plus, its higher neckline helps keep frigid air out.
Sizes: XS to XXL | Materials: Polyester, elastane
Kari Traa Rose Half-Zip Base Layer Top
Pros
- Odor-resistant
- Quick-drying
- Adjustable coverage
Cons
Both Kreis and Peikon suggest a half- or quarter-zip top if you want more temperature control: Fully zipped, it provides full coverage; unzipped, it releases some body heat. Kreis likes this option from Kari Traa because it’s 100% Merino wool, one of his top-recommended fabrics for base layers (it’s also made with four-way stretch, so it doesn’t feel stiff).
REI and Backcountry reviewers say the Rose Half-Zip is impressively warm—one wrote that it’s all they wear under their ski coat when they hit the slopes.
Sizes: XS to XL | Materials: Merino wool
Smartwool Classic Thermal Merino Base Layer Crew
Pros
- Very soft
- Good for a wide range of temperatures
- Lots of color options
Cons
- Runs small, according to Smartwool reviewers
This SELF Activewear Award–winner kept our tester warm while hiking a four-mile, snowy mountain trail in 32-degree weather. “The material was very soft, not itchy at all, and comfortable,” she said, adding that she’d happily sleep in it on her next backpacking trip. Plus, the fit is great if you’re going to be moving around a lot: “The body of the shirt was fitted, but the sleeves were slightly loose,” our tester said. “That offered the mobility I need when hiking and scrambling.”
What sets this Smartwool layer apart from the Intraknit shirt above is its materials and purpose: The Classic Thermal Merino Crew is 100% wool and made to perform in the coldest temps, while the Intraknit is better suited for cool-to-cold weather between 25 and 50 degrees.
Sizes: XS to 4XL | Materials: Merino wool
Janji Rover Merino Hoodie
Pros
- Hooded
- Bottom hem pocket for small items
- Not quite as snug as other options on our list
Cons
Our director of fitness and food also likes this Janji hoodie, noting that it isn’t bulky in the least—instead, it fits close enough to the body that you can wear a vest over it. It also has a snug hood that won’t slide around while you’re on the move and sleeves with thumb slits, so you get a little more coverage than you would with a standard long-sleeve crew.
Sizes: XS to 3XL | Materials: Merino wool, nylon, spandex
Athleta Ascent Seamless Top
Pros
- Very stretchy
- Under $90
- Ventilated mesh panels
Cons
- Not suitable for very cold weather
Here’s a breathable base layer for milder days “when you need something under your T-shirt, but know you’ll be sweating buckets if you wear anything too heavy,” our senior commerce writer says. She put it to the test on several classically fickle spring days, where the sun was shining one moment and it was chilly and breezy the next. “It added a little warmth when I needed it, and helped me stay cool when I peeled off my other layers,” she says, adding that it has “seemingly limitless amounts of stretch.”
Sizes: XXS to XL | Materials: Nylon, wool, spandex
Best base layer tights and leggings
Minus33 Lightweight Magalloway Merino Wool Bottom
Pros
- Available in three weights
- Holds up after many washes
- Under $80
Cons
- Amazon reviewers report some inconsistencies with sizing
SELF’s lifestyle director wears Minus33’s Lightweight Magalloway Merino Wool base layer under running pants and jeans, which we consider a testament to how light they truly are. “They’re really soft and warm, but not too warm,” she says. “They’re not too tight and don’t dig into your waist, and they wash well.”
These tights are also available in a midweight variety and the brand’s “expedition” weight, which is the warmest, heaviest option (Minus33 recommends it for 30-degree weather and below).
Sizes: XS to 3XL | Lengths: 26 to 32 inches, depending on the size | Materials: Merino wool
Columbia Omni-Heat Infinity Tights
Pros
- Sweat-wicking
- Under $65
- Lightweight but warm
Cons
- Waistband could be wider, per one tester
Columbia’s Omni-Heat Infinity Tights won a 2023 Activewear Award for their impressive heat retention. Their lining reflects and traps your body heat, but wicks away sweat so you can stay dry. “I wore only these as bottoms while hiking in 32-degree weather (with no other base layers),” one tester said. “The leggings were not only warm, but were flexible and responsive with my movement. I’ll be wearing these on more hikes and camping trips to come.”
The Omni-Heat Tights are also a standout for one SELF staffer, who’s looking forward to wearing them skiing. “These are way warmer than other base layers I’ve tried,” she says. “They’re lightweight, fit perfectly, and have held up over time.” She also recommends the corresponding Omni-Heat Infinity Base Layer Crew shirt for all-over lightweight warmth.
Sizes: XS to XXL | Length: 26 inches | Materials: Polyester, elastane
Kari Traa Rose Capri High-Waist Base Layer Bottoms
Pros
- Pair well with ski boots
- Very soft
Cons
Kreis also recommends Kari Traa’s Rose capris, which end right below your knee. This length can come in handy if you’re wearing them with ski boots or other high-cut, heavy footwear, since they won’t add extra bulk around your lower legs. And the areas they do cover will be nice and warm, thanks to their soft-to-the-touch wool fabric and midweight insulation.
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