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16 Best Base Layers for Extreme Cold in 2024

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Layering while out in extremely cold weather is critical to staying warm, dry and alive! When the mercury drops, your core body naturally wants to drop too!

We are not naturally made to be outside for long periods of time. This is why it’s so important to wear layers made out of the right material.  The sole function of the base layer is moisture management.

When you’re hiking, climbing or even setting up camp, you’re bound to work up a sweat.  The base layer is intended to wick away that moisture from your skin!

In this article we will give you our take on the best base layers for extremely cold weather.

Our Favorites…

Base Pro Crew Neck

Fortress Clothing BasePro Crew

Stay warm wet or dry

Rated for -5°F to 70°F

4-way stretch

BasePro Pant

Fortress Clothing BasePro Pant

Stay warm wet or dry

Rated for -5°F to 60°F

4-way stretch

Icebreaker Oasis Long Underwear Top

Icebreaker Oasis Base Layer Top

100% Merino Wool

Soft, comfortable, breathable

Chafe-free seams

16 Warmest Base Layers for Extreme Cold

1. Fortress BasePro Crew

Fortress Clothing BasePro Crew Neck

If you’re heading into the back-country to camp under the stars in mid-January, take the Fortress BasePro Crew with you. 

PROS: Wicks away moisture, insulated, keeps you warm when wet, rated for -5 to 70 degrees F, replaces the need for a middle layer, comfortable.

CONS: May be too bulky for high intense activities. 

This well made, durable and versatile base layer is all you need to stay dry while camping, hiking and ice fishing in the great outdoors. Fortress is a Utah based company revolutionizing the way we think about outdoor gear.

The company developed a patented insulation, AERIS, that keeps you warm even if you become fully submerged in water! Even if you don’t fall in an ice hole, this base layer will wick away sweat faster than the winning car at the INDY 500. Because it’s insulated, this is like wearing a base layer and middle layer in one! It’s lightweight, durable and fits close to your skin.

The layer is made with 4-way stretch, so it moves with your body- preventing restriction and early wear and tear in high impact areas.  This layer is also breathable so that sweat can move up and away from your body with ease. 

Check them out here: Fortress BasePro Crew

2. Fortress BasePro Pant

Fortress Clothing BasePro Pant

The BasePro Pant compliments the BasePro Crew and are designed to be worn together for an ultimate base layer.

PROS: Comfortable, AERIS insulation, lightweight, warm when wet, wicks away moisture, breathable, adjustable waist.

CONS: Higher end of price range.

The BasePro Pant is what you want to be wearing when it’s bone chilling cold outside and you’re craving a mountain adventure – they are some of the warmest pants around. 

Even if you’re not into scaling peaks, these are great for cold soccer Saturday’s, watching your kids score another goal! Go team! The pants are insulated with AERIS loft in areas prone to getting chilled- quads, knees and the back of your legs.

Because they are insulated, you don’t need a middle layer with these pants! They are lightweight, breathable, durable and incredibly comfortable. With the BasePro rated for -5 to 70 degrees F, you can literally wear these pants all year round.  The pants also keep you warm when wet, so you don’t have to worry about sweat bringing you down!

Check them out here: Fortress BasePro Pant

3. Fortress BasePro ¼ Zip Top

Fortress Clothing One Quarter Zip Top

The BasePro 1/4  Zip Top allows you the freedom to regulate your body temperature with a simple zipper. 

PROS: Insulated, wicks away moisture, can substitute for a middle layer too, warm, great for industrial workers, recreation and survivalists.

CONS: Bulky.

The 1/4  zip is great for those who need to cool off without releasing a whole lot of body heat.  I imagine this would come in handy when you reach the top of vista in the mountains and you need a breather and a granola bar.  This layer is made with AERIS insulation and polyester mesh.  It’s rated to keep you dry and warm at -5 to 70 degrees.

The revolutionary material used in this base layer will keep you warm, when you overestimate the depth of that river! Who me? Yes YOU! Even if you don’t fall in a river, you’ll most certainly be wet, but you will still be warm. This layer is really comfortable, moves with your body and is great to wear all season!

Check them out here: Fortress BasePro 1/4 Zip Top

4. Icebreaker Oasis Long Underwear Top

PROS: 100% merino wool, soft, comfortable, warm, breathable, moves with your body, slim fit, versatile, seamless design, extra-long sleeves.

CONS: Runs small.

Icebreaker Oasis Long Underwear Top is made with a whopping 100% merino wool. All that wool means you will be fully protected from sweat.

This means you will be dry and warm at all times- from the campsite to the day hike- this pair of long underwear has you covered- literally. This long john top is lightweight, making it a great option for sleeping in and wearing during intense activities.

The merino wool is really soft, making it oh-so comfortable no matter where you are and no matter what the temperature.

Check it out here: Icebreaker Merino Men’s Oasis Crew

5. Icebreaker Oasis Leggings

Icebreaker Merino 104369 Men’s 200 Oasis Leggings, Medium, Black/Monsoon
  • Updated design
  • Icebreaker branded brushed elastic waistband
  • Flatlock seams prevent chafing

PROS: Warm, 100% merino wool, soft, comfortable, elastic waist, lightweight.

CONS: May need another layer when camping in extreme cold.

The Oasis Leggings are the perfect match for the Oasis Long Underwear top.  With this set, you will be all set to camp during the winter months. Like the top, these leggings are made with 100% merino wool. 

This means you are guaranteed to stay warm and dry while sleeping and while getting to your favorite campsite.  The fit is slim and can be worn alone or as a base layer with a mid-layer on top.

The slim fit allows for more layers to be added as the weather changes.  Even with adding layers, you won’t feel restricted because of the slim fit.

Check them out here: Icebreaker Oasis Leggings

6. SmartWool Merino 250

Smartwool Men’s NTS Mid 250 Crew, Black, Large
  • Slim Fit
  • Interlock knit
  • Crew neck with set-in sleeves

PROS: 100% merino wool, wicks away moisture, keeps odor away, breathable, seamless construction, medium to heavyweight.

CONS: Sells out quickly, hard to find.

The SmartWool Merino will give you the confidence to explore, hike, climb and camp anywhere your heart desires.  Setting up tent on the edge of snow covered cliff? You got this!

The Merino 205 is a quarter zip long sleeve base layer packed with a whooping 100% merino wool! This a medium to heavy weight garment so this is perfect for really cold nights inside the tent.  In fact, this is the warmest base layer top SmartWool makes!

It’s comfortable with flat seams to prevent chaffing.  This layer also zips at the neck 1/4- making it easy to adjust your temperature depending on the weather and your level of activity! Not only is this the warmest garment, it wicks away moisture-keeping you dry all the time.

Check it out here: SmartWool Merino 250

7. SmartWool 250 Bottom

PROS: Warm, wicks moisture, slim fit, heavyweight, elastic waist band, made for extreme cold.

CONS: May be too warm for intense activity.

Going somewhere? Put on pair of SmartWool Merino 250 Bottoms and you’ll be warm and dry no matter where the trail leads you! Like the matching top, these pants are literally the warmest base layer SmartWool makes.  They are slim fit-making them a great choice for a base layer.  The pants are made with 100% merino wool.

I love these pants because they are naturally warm, wick away moisture like a boss and they are breathable.  Seamless design makes these pants exceptionally comfortable to wear all day and all night.  You’ll want to wear these to bed inside your tent too!

Check them out here: SmartWool 250 Base Layer Bottoms

 8. SmartWool Merino 150 Long Sleeve

PROS: Lightweight, merino wool and nylon blend, slim fit, seamless design for added comfort, breathable.

CONS: Not intended for sub-zero temperatures.

Climb into your sleeping bag with this long sleeve base layer on and you’ll be so warm you’ll be dreaming of warm sand and palm trees. The 150 merino is lighter than the 250 as I listed earlier in this article.  The 150 is designed for cold weather, but not extreme temperatures into the back-country.

You know those summer days where it’s 75 during the day, but the 7,000-foot elevation means it’s going to be chilly at night? This is what you want to have on- not too hot, not too cold. Just right, like your mom’s famous mac and cheese.  Just right!

This shirt is made with 87% merino wool and 12 % nylon.  The nylon is added for durability- you could camp in these several nights in a row and not worry about odor! Phew. 

Check it out here: SmartWool Merino Sport 150 Long Sleeve Top

9. Helly Hansen Merino Mid Pant

PROS: Made for extreme cold, lightweight, 100% merino wool, breathable and snug fit to keep layer of warm air close to your body.

CONS: Runs large. 

The merino mid pant is the perfect pair of base layer pants to wear on your next camping adventure.  With 100% merino wool wrapped around your legs at all times, you are sure to be warm and dry in the mountains and in the valleys. 

The flat lock seams make this base layer pant extra comfortable and cozy.  These are so comfortable, you may be tempted to wear them everyday of your camping trip.

You may even find yourself wearing them as pajamas.  These are designed for extreme cold weather!

Check them out here: Helly Hansen Merino Mid Pant

10. Helly Hansen LIFA Merino Crew

Helly-Hansen Men’s LIFA Merino Baselayer Crew Top, Black, X-Large
  • 2-in-1 baselayer, 2-layer construction, 100% merino wool exteriour, Lifa technology interiour
  • Non itch , Flat lock seams , 225g/m2

PROS: 2 in 1 base layer, 100% merino wool, soft, medium weight, comfortable, designed for extreme cold weather conditions.

CONS: Tags can be scratchy.

This is the warmest base layer long sleeve shirt Helly Hansen makes. It’s a 2 in 1 base layer- it will keep you dry and it’s insulated to keep body heat close to your body. This garment eliminates the need for a mid-layer.

This shirt is perfect for those extra cold nights in the mountains when you are wondering how you ended up there.  Don’t go there. These pants keep you warm and make sure you keep a positive attitude during your warm winter camping excursion.

The pants are made with 100% merino wool! That means you will be warm, dry and comfortable no matter what’s going on outside your tent. 

Check them out here: Helly Hansen LIFA Merino Crew

11. Icebreaker 260 Zone Base Layer Top

PROS: 96 % merino wool, Lycra for stretch, breathable, special venting fabric to keep sweat moving away from your body, slim fit.

CONS: Runs small.

This is mid-weight long sleeve shirt packed with merino wool and Lycra for stretch and comfort.  Because it’s mid-weight this will be a perfect shirt for cold winter nights under the stars.

The long sleeve is also great for high intense training and outdoor adventures and the seams are flat to reduce any chaffing you may encounter while hiking or setting up camp. 

Check it out here: Icebreaker 260 Zone Base Layer Top

12. Icebreaker 260 Zone Base Layer Leggings

Icebreaker 260 Zone Legging – Men’s, Midnight Navy, L
  • Responsible Collection: Responsibly Sourced
  • Material: [body] 97% wool, 3% lycra, [panels] 78% wool, 22% polyester
  • Insulation Weight: heavy

PROS: 96% merino wool, Lycra for comfort and mobility, keeps moisture away, breathable, warm!

CONS: Runs small.

With the 260 Zone leggings, your legs will be warm and dry no matter what happens in the mountains.  Weather can change quickly when you’re camping at 5,000 feet.  These leggings can adapt quickly too, keeping you warm and dry in a variety of conditions.  The leggings are made with 97% merino wool and 3% Lycra.

This unique blend of material means this base layer will move with your body, no matter what you have planned for the day! Plus, the odor resistant material means you can sleep in these leggings and wear them the next day- no one will know!  Your secret is safe with us!

Check them out here: Icebreaker 260 Zone Base Layer Leggings

13. The North Face Men’s Warm Tights

THE NORTH FACE Men’s Winter Warm Tight, TNF Black, L
  • FACE THE WEATHER. The fitted Winter Warm Tight is water-repellent and features moisture wicking FlashDry throughout. These sleek trail running tights also have zoned-in WindWall technology on the…

PROS: Warm, stretchy, comfortable, moves with your body.

CONS: May be too tight for some builds. 

The Warm Winter Tights are a budget friendly way to stay warm while camping in the snow!  You get a pair of high quality pants that will keep moisture away and allow that nice warm pocket of air to stay close to your skin at all times.

The tights are made with a polyester blend designed to keep you warm, dry and free of odor. 

Check them out here: The North Face Men’s Warm Tights

14. Arc’Teryx RHO LT Bottom

Arc’teryx Rho LT Bottom Women’s | Lightweight Torrent Base Layer – Redesign | Black, Large
  • RHO LT BOTTOM WOMEN’S – Lightweight, effective, and comfortable, the Rho LT is your base layer for low and medium output on cold days.
  • RHO – Thermally efficient base layer with excellent moisture management properties. Has stretch comfort.
  • LIGHTWEIGHT – High performance, minimalist design that is durable for its weight.

PROS: Lightweight, polyester blend, warm, fleece lined, keep you dry, medium weight.

CONS: Due to popularity these pants sell out fast!

If the snow starts to fly and you’re camping in the back-country, climb into your sleeping bag with the Arc’Teryx RHO LT Bottom. With these fleece, lightweight and breathable pants, you’ll be warm no matter what is going on outside your tent.  These pants won’t protect you from bears, but they’ll keep you safe from sweat- and that’s pretty cool.

This base layer is designed to keep you warm when you’re resting.  The elastic waist means you can move with ease on your next adventure and sleep comfortably under the stars or under a down sleeping bag.

Check them out here: Arc’Teryx RHO LT Bottom

15. Patagonia Capilene Thermal Weight Bottoms

Patagonia Capilene Thermal Weight Bottoms

This base layer will go where ever you want to go.  The top of Mount Blanc? Sure. Trudging through snow to set up camp on the shore of a northern Minnesota lake?

Okay, I’ll bring the marshmallows.  

PROS: Durable, last for years, polyester blend wicks away moisture/sweat, comfortable and flat seams reduce chaffing. 

CONS: Limited sizes, sell out quickly

Seriously, Patagonia knows how to create durable base layers you will wear when Mother Nature puts on a show.  These pants are made with polyester, spandex and a special odor control liner to keep you feeling fresh even when you’re on day five of a winter camping adventure.

This base layer features an open-design grid allowing the pants to get close to your skin and keep moisture away! The elastic waistband allows you to move with ease and what the heck, have a few smore’s around the campfire. 

Check them out here: Patagonia Capilene Thermal Weight Bottoms (Men’s) and Women’s

16. Patagonia Capilene Thermal Weight Zip-Neck

Patagonia Capilene Thermal Weight Zip-Neck.

The Thermal Weight Zip Neck is a great way to ensure you will be warm, even with a blizzard shaking and whipping your tent around. 

PROS: Warm, polyester blend, elastic waist, wicks moisture, slim fit, back of shirt longer for more protection and coverage, thumb loops and seamless comfort.

CONS: Runs large.

The thermal zip neck is the heaviest weight base layer Patagonia makes. I especially love the elastic thumb holes that keep your sleeves in place and your wrists covered at all times. This is a great layer to sleep in- you won’t wake up with the sleeves pulled up and your arms cold.

The long sleeve is made with polyester which will keep you warm and dry no matter what the weather. The shirt is a slim fit, giving you more options for a middle and outer shell without the bulk.

Check it out here: Patagonia Capilene Thermal Weight Zip-Neck Top (Men’s) and Women’s

Choosing the Right Base Layers

When choosing a base layer, you need to look for wool, polyester, nylon, acrylic or another synthetic material.  These materials naturally move sweat off your body! Plus, wool and synthetic materials are also really good at insulating your body. 

If you’ve been following my blog, you know how I feel about cotton. If you’re a new reader, welcome- let’s talk about cotton.  Stay away from cotton at all costs. Cotton is comfortable, but it’s downright dangerous when you’re outside in the bitter cold.

Cotton fiber has a sneaky way of absorbing water/sweat and holding onto it like a wet sponge. If you wear a base-layer made out of cotton, before you know it you’ll be soaked and the clothes will actually draw body heat away from your core.

Many outdoor guides and search/rescue teams will inspect every garment a fellow hiker/rescuer is wearing before they even step foot on the trail.  Cotton is not allowed in the mountains- and it seriously could mean the difference between life and death.  So, double check those labels before you purchase your base-layer.

The base layer should fit snug against the body, right next to your skin. Not too snug where you can’t move your arms around or naturally move your legs around- just close enough to your skin to wick moisture away and stay comfortable.  In addition to wicking away moisture, the base layer also traps a thin layer of warm air close to your skin, keeping you warm and dry no matter what Mother Nature decides to do.

You’ll notice while shopping for a base layer, the garment comes in a variety of weights: lightweight, medium weight and heavy weight.  Lightweight is intended for cool temperatures, anything above freezing.  Mid-weight is a great choice for temperatures hovering around freezing and you’ll want to grab the heavyweight long johns when it’s below zero.

Keep in mind your activity level too. If you are exerting a lot of energy and climbing to the top of Denali you may want to go with a mid- to lightweight base layer- even though it’s cold.  While the weight of the fabric generally means it will keep you warmer, it’s really not as important as what the garment is made out of.  Remember, the base layer is for moisture management, not insulation- that’s where the middle layer comes in!

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Hi! I’m David. For most of my life I have been interested in emergency preparedness. Over the many years things have changed a great deal. From freeze dried food, to LED lanterns, preparing for an emergency has never been easier. The continual research I have done over the years has become the basis for this website. Now it is one of the most trusted sources to learn about emergency preparedness.