Thermals, long johns, base layers – whatever you want to call them, there’s nothing like a warm layer worn next to the skin to help keep the chill of colder weather at bay.
Whether you’re skiing, hiking or cold-weather camping, layering up is the best way to trap in heat and keep cosy in the great outdoors, and a good layering system starts next to the skin with a quality base layer set of top and leggings.
The best base layers should hug your body, without feeling too restrictive around the waistband, ankles, neck or sleeves. Some base layers are stretchier than others – we found thermals with some stretch offered more warmth on test, as there’s no empty space between the fabric and your skin for the cold to creep in. Base layer tops usually have a crew neck or a high, zipped neck – the latter can double up as a neck warmer, and some tops also sport hoods, for extra warmth. Look for base layers that use ‘flatlock’ sticking, to avoid any rubbing against your skin.
Many base layers are made with synthetic materials, such as polyester, but the best base layers are made with a percentage of merino wool (though, they will be pricier). Merino is very warm but still highly breathable and is great at wicking away sweat. It also has naturally antimicrobial properties, making it perfect if you’re getting active or heading into the backcountry without a shower in sight. Even better, try alpaca wool – it performs just as well and tends to be produced more sustainably.
Bamboo base layers are more recent arrivals on the market – they’re also great options, as they’re soft to wear, antimicrobial and more eco-friendly to produce than synthetic materials. You may see base layers listed with a number, such as 140 or 220 – this refers to their weight in grams, and the higher the number, the warmer, but heavier, the base layer.
How we tested
We tried out each of these base layer sets during autumn hiking and camping trips, wearing the base layers alone and under waterproofs and testing for warmth, comfort and breathability. We were looking for base layers that added instant warmth, felt comfortable under other layers and were breathable on the go. Base layer no-nos? Feeling itchy or restrictive, not wicking away sweat and not feeling soft and flexible against the skin.
Why you can trust us
Sian Lewis is an award-winning travel and outdoors journalist and has written for IndyBest since 2020. Adept when it comes to assessing outdoor gear, Sian has previously brought readers her verdict on the best camping gear, hiking gear, and winter sports equipment on the market, including the best snow boots, thermal socks and ski gloves.
The best base layers for 2024 are:
66 North básar merino base layers
66 North has created the holy grail – the perfect 100 per cent merino base layer set of top and bottoms. They are just a joy to wear – warm, delightfully soft against the skin, stretchy and flattering. We liked wearing these pieces so much, we found ourselves reaching for them daily, whether we were off hiking or skiing or just walking in the park. They hold up well after washing, and we reckon the zip-neck top is smart enough to pair with jeans. These base layer beauties are expensive but they’re worth the investment if you’ll wear them regularly.
Buy now £135.00, 66north.com
Sockshop Heat Holders thermal leggings
These simple thermal bottoms trap in heat well and feel soft against the skin. The thin material works well layered under tighter salopettes, jeans or an outer pair of trekking tights but these thermal bottoms can’t really be worn as standalone leggings (especially not the translucent white pair). The quality is decent for the affordable price – a good choice if you just need bottoms for your first ski holiday or for occasional use.
Buy now £24.99, Sockshop.co.uk
Mountain Warehouse Isotherm Thermal
Good base layers can be surprisingly – even shockingly – expensive. If you’re off on a beginner ski trip or just want something you can pull on for cold-weather dog walks or an especially chilly school run, however, you can’t beat Mountain Warehouse for budget-friendly base layers. If you do want a decent set that is warm yet breathable for sport, we rate the brand’s merino base layers set – you get all the benefits of merino wool at a bargain price.
Buy now £59.99, Mountainwarehouse.com
Patagonia R1 thermal bottoms
Half thermal legging, half sweat pant, there’s lots to like about these fleece trousers, which were one of the warmest we tested – they trap in heat fast, feel lovely and soft and can be worn both as a base layer and as standalone trackie bottoms, thanks to a comfy wide waistband and tapered fit. We liked the more casual cut of these stretchy pants, which can be worn pretty much anywhere, from work to mountainside. It’s just a pity the R1 costs an arm and a leg, although buying from Patagonia is a planet-friendly choice – here, the fabric is recycled and Fair Trade.
Buy now £160.00, Patagonia.com
Paka thermal base layer top and bottoms
Paka reckon alpaca wool is the “cosiest fibre evolved in nature”, and it’s also a more sustainable option than synthetic materials. Paka sources its wool from free-roaming alpacas in the Andes, and each garment is fully traceable to the animals they sheared – so, if you like knowing exactly where your kit is coming from, this is a good place to shop. We tried out the thermal top and bottoms, both of which are sleek, simple and soft, and kept their shape well after regular use and washing. Although we’d have liked a wider waistband on the bottoms, all in all, this pair is a sustainable and smart way to stay cosy.
Buy now £100.00, Pakaapparel.com
Falke tights warm
Who needs bells and whistles on their base layers when Falke makes such simple and effective thermals? These thermoregulating tights do a great job at trapping body heat as well as wicking away sweat, if you’re getting active, so they’re great for bursts of movement in the cold. Besides that, they are pleasingly minimalistic, fit close to the body and offer totally unrestricted movement, so they’re ideal for skiing and climbing. While these tights don’t boast merino wool, they do use recycled polyester.
Buy now £62.00, Falke.com
Arms of Andes alpaca wool half zip
Another great option that uses the warmth of alpaca wool, this half-zip top is light, breathable and easy to layer. The zip allows for further ventilation or zips up to offer a little more neck protection. We also love that you can choose from ‘low-impact’ dyes, making your new top a more sustainable pick. Overall, this is a high-quality, versatile base layer that is ideal for active and eco-minded individuals.
Buy now £87.27, Armsofandes.com
The North Face summit pro 120 crew top
If you like to feel as unencumbered as possible when you’re layering up for the cold, give The North Face’s relaxed summit pro top a try. Cut long, it sits on the hips and allows a bit more breathability, so you can also wear it as a mid layer over a vest. At just 160g, despite feeling light to wear, the crew retains heat fairly well. It really excels when you’re moving fast, as it wicks away sweat to keep you cool, making it a great choice for fast-moving climbers and mountaineers.
Buy now £90.00, Thenorthface.co.uk
BAM bamboo thermo luxe top
Ultra-comfy, organic and highly breathable, bamboo fabric is a fantastic material for sportswear. Effective antibacterial properties make bamboo a clever choice for camping or backcountry expeditions: you can hike for days in this anti-odour base layer jersey without offending the noses of your hiking companions. BAM’s sport-friendly base layers aren’t just comfortable – they’re smart enough to wear when you aren’t out on the trail. The stretchy thermo luxe top is comfy whether you’re walking, climbing, skiing or cycling, and we also love the thumb holes.
Meanwhile, the Mallea leggings (£41.26, Bambooclothing.co.uk) are designed for yoga but double up well as general base layers, and the crossover design of the waistline is the most flattering we’ve tried.
Buy now £39.00, Bambooclothing.co.uk
Icebreaker zoneknit base layers
Base layers are what Icebreaker does best, and they’re always some of the top-performing designs when we test thermals each winter. Icebreaker’s merino layers are worth the spend, and will last you for years, without losing their shape or their warming abilities. It’s easy to mix and match the thermals on offer, but we like the combo of the 260 weight zoneknit crewe top and the stretchy zoneknit seamless tights, which fit brilliantly, thanks to a high, wide waistband. There’s extra coverage on the bottoms, so you can wear these by themselves, too.
Buy now £125.00, Icebreaker.com
Montane protium lite hooded fleece jacket
Half hoody, half base layer, this is a clever bit of kit that you can pop over underwear or a vest top and layer under a thicker mid layer, for that extra hit of warmth on the coldest days. The hood is handy for keeping you protected from the elements and the slim yet stretchy fit is really flattering and comfortable, with flatlocked seams to stop you feeling any rubbing. At just 215g, this is a layer that definitely won’t weigh you down but that will add welcome warmth during trekking, skiings and other mountain adventures.
Buy now £90.00, Montane.com
Dope snuggle top and leggings
Most base layers aimed at snow-sports enthusiasts come in boring black and grey colourways – if you want to stand out, though, head to Dope. The brand’s snuggle range of tops and leggings for men and women come in bright, beautiful patterns (as well as smart neutral colours) and are pleasingly stretchy and easily to layer under ski jackets. They will work well for yoga and trips to the gym, too. A matching face mask is also included with the snuggle top.
Buy now £51.00, Dopesnow.com
Icebreaker 200 oasis crew top
If comfort is top of your list, slip these base layers on and the first thing you’ll notice is how deliciously soft their 100 per cent merino wool make-up feels against the skin. The 200g weight is a good warmth-to-weight ratio for most outdoor adventures, and our top pick in the range is this simple and form-fitting crew top, which fits so nicely you’ll barely notice you’re wearing it. A lovely choice if you’re after merino.
Buy now £85.00, Trekitt.co.uk
My Sunday Ski racer stripe base layer set
Fancy something a little different? My Sunday Ski does a fine line in style-led ski gear that would make any fashionista proud – think shiny puffas, posh cashmere and lots of faux fur. This smart base layer set with go-faster racing stripes is great for lounging at the chalet (or just at home on the sofa) and is brilliant worn under form-fitting ski outer wear. A turtleneck and high-cut bottoms make these comfy, warm and breathable base layers high performers, and, at £85 for the set, they’re decent value, too.
Buy now £85.00, Mysundayski.co.uk
The verdict: Base layers
The 66 North básar merino base layers are worth the investment if you’re after great thermals that will last. Alpaca wool is a lovely (and more sustainable) fabric, so, try Paka’s and Arms of Andes’s excellent layers. For more casual kit you can wear daily during winter, BAM’s bamboo tops and leggings and Patagonia’s trackie-style bottoms are top choices.
Want more winter sports essentials? Check out our review of the best ski goggles
