If you’ve ever been drenched with sweat on a bootpack, then frozen on a chairlift five minutes later, you already know the truth: ski baselayers matter. The right base layer is what keeps your temperature stable, moves moisture away fast, and stays comfortable through changing intensity - whether you’re skiing pistes, touring, or chasing storm days.
In this guide, we’ll focus on merino wool ski baselayers, and specifically Aclima of Norway - a Norwegian wool specialist brand known for smart fabric engineering and a range structure that actually makes it easy to choose the right kit for the day. Nordic Outdoor stocks a comprehensive Aclima selection in the UK, including their best-known merino baselayer ranges.
What makes a great ski baselayer?
A high-performing ski baselayer should do five things well:
- Move sweat away from skin (so you don’t chill when you stop)
- Regulate temperature across conditions (uphill vs downhill, wind, snowfall, sun)
- Stay comfortable for long days (soft hand-feel, flat seams, good stretch)
- Resist odour (especially on multi-day trips)
- Layer cleanly under midlayers without bunching
Merino wool is popular for skiing because it balances warmth and breathability, and tends to be more comfortable and soft on skin than synthetics - particularly when you’re layering for long days.
What sets Aclima apart from other baselayer brands?
With a history stretching back nearly 100 years Aclima positions itself as a wool specialist with deep heritage (they are of course the “Wool Specialist Since 1939”), and builds ranges around specific performance needs rather than one-size-fits-all “thermal underwear.”
Three clear differentiators stand out when looking at what sets Aclima apart from other baselayer brands:
- A genuinely engineered system approach: Aclima’s collections span ultra-light merino through to expedition-grade insulation, including specialist constructions like mesh (net) baselayers and terry-loop interiors.
- WoolNet (mesh merino) as a signature technology: Designed to trap warm air when static, then dump excess heat when moving - particularly relevant to skiing, touring, and stop-start winter days.
- Purpose-built cold-weather lines: For example, HotWool was developed for the Norwegian Armed Forces and uses a terry-loop construction for insulation and durability in extreme cold.
Aclima’s key merino ranges for skiing (and how to choose)
1) WoolNet Original: the “runs hot” skier’s secret weapon
If you tend to overheat on traverses, hike-to terrain, or ski touring transitions, WoolNet Original is one of the most practical baselayer choices you can make.
Aclima describes WoolNet Original as the “original merino wool mesh,” engineered for extreme moisture transport and temperature regulation; the open structure traps warm air when you stop and ventilates efficiently when you move.
Best for
- Resort skiing if you sweat easily
- Ski touring and high-output skiing
- Layering under a shell where moisture management matters most
2) WoolNet Light: maximum ventilation for high-intensity or warmer days
WoolNet Light is Aclima’s lightest merino mesh option - built for high-intensity activity and warmer conditions. The technical construction is explicitly designed to create insulating air pockets at rest and release heat during movement.
Best for
- Spring touring
- Fast uphill days
- Warmer climates or “sunny but cold wind” days
3) WarmWool: the classic merino ski baselayer for cold conditions
WarmWool is Aclima’s most popular collection, positioned as versatile merino garments that stay warm in cold conditions while remaining breathable during activity.
From a ski baselayer perspective, WarmWool is the reliable choice when you want more fabric weight, more insulation, and a more traditional baselayer feel. Many WarmWool styles are in the ~220–225 g/m² range, designed to keep you warm and dry in demanding weather.
Best for
- Resort skiing and chairlift-heavy days
- Cold snaps and windy conditions
- Anyone who prioritises warmth and comfort over maximum venting
4) LightWool 140: featherlight merino for high-output layering
LightWool 140 is Aclima’s lightest 100% merino collection, intended for warm days and high-intensity training when you need a base layer that breathes and feels soft against skin.
Aclima also states LightWool uses 17.5 micron yarn with a fabric weight of 140 g/m², positioning it as exceptionally soft.
Best for
- Ski touring base layer (especially if you add insulation over the top)
- Mild resort days
- People who want “barely-there” feel under layers
5) LightWool 180: the year-round merino “do-it-all”
LightWool 180 is built as a year-round, lightweight merino option - still breathable and odour-resistant, but with more warmth than 140. Aclima lists 100% merino, 19.5 micron, and 180 g/m² as technical details.
Best for
- Mixed-intensity days (resort + short hikes)
- People who want one merino baselayer for multiple sports
- Travel: one layer that works across trips
6) HotWool: for very cold conditions, low output, or maximum insulation
HotWool is designed for harsh conditions and extreme cold, developed for the Norwegian Armed Forces. It combines merino with reinforcing fibres, and the terry loop construction is designed with loops facing the skin for insulation and comfort.
Best for
- Coldest resort days (especially if you stand around a lot)
- Photographers, instructors, spectators, or low-output users
- Deep winter trips where warmth margin matters
Other Aclima collections worth knowing (system depth)
Aclima’s broader range list also includes lines such as WoolNet Hybrid, FleeceWool, FlexWool, DoubleWool, DesignWool, ReBorn, etc., which speaks to how extensive the system is.
For skiing, most customers will start with WoolNet / WarmWool / LightWool, and then build outward.
Practical “pick your Aclima ski baselayer” shortcuts
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You ski hard and sweat easily (or you tour): start with WoolNet Original or WoolNet Light.
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You want a classic warm merino ski baselayer: choose WarmWool.
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You want one merino layer for most of the year: choose LightWool 180.
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You feel the cold, ski lifts all day, or want maximum warmth: look at HotWool.
- Your looking for something comfortable and warm for Apres Ski: Choose Aclimas’ Fleecewool collection
Baselayers covered, what’s next?
If you’re heading out to the slopes and are looking for the right kit to make the most of your adventure then we’re here to help. Alongside our Merino Wool Baselayers we have expanded our ski collection this season to include some of the best ski jackets of 2025, ski trousers from top Scandinavian brands and Ski Gloves from Hestra.
You can shop the full Ski collection online now or head instore to learn more.
