THE cold weather is creeping in, and it won’t be long before we’re layering up with our warm winter clothing.
Thermals make a great base layer for staying cosy in cold climates, and we’ve put some of the best thermals for women to the test.
An extra warm layer makes the weather change that much more bearable, which is why they don’t need to be limited to outdoor activities.
Thermal underwear is the perfect accompaniment for skiing and hiking, but the warm layers will also be a saviour for everyday wear in the depths of winter.
Commonly in the form of leggings and tops, thermals can be worn beneath regular clothes, acting as a cosy added layer that insulates the body.
The base layers will have a snug fit to lock in the heat, but the best options will be warm and comfortable without feeling restrictive.
High-quality base clothing is often made from merino wool, as the material is moisture-wicking and therefore keeps you warm in the cold and cool in the heat.
Gone are the days of thermals for women being clunky and impractical.
Several high-street retailers have got in on the action, with stylish options stocked at Marks & Spencer and Uniqlo.
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Best thermals for women at a glance
- Best overall: M&S Heatgen Thermal Scoop Neck Top, £17
- Best thermal leggings: Pour Moi Second Skin Thermal Leggings, £25
- Best thermal top: Pour Moi Second Skin Thermal Long Sleeve Top, £25
- Best for cold weather: Uniqlo Heattech Ultra Warm Crew Neck T-Shirt, £24.90
- Best for skiing: Mountain Warehouse Merino Zip Neck Thermal Top, £34.99 (was £59.99)
How I tested
I put thermal leggings, tops and fleeces to the test, trying them across days and weeks to determine if they’re worth it.
During testing, I considered the quality, style, range of sizes/ colours and each item’s value for money.
Most importantly, I was looking out for how effectively each thermal base layer insulated the heat and kept me warm.
I wore the thermals beneath several different items of clothing to see how well each one worked as a base, testing them throughout an entire day and evening to assess the comfort.
I’ve also tried-and-tested the best leggings for women.
Thermal tops for women
M&S Heatgen Thermal Scoop Neck Top
M&S Heatgen Thermal Scoop Neck Top, £17
Pros: Comfortable, soft lining, stretchy fit, looks stylish, affordable, sits nicely beneath under clothing, four colour options
Cons: May be too thick for some
Rating: 9/10
Marks & Spencer launched its Heatgen range back in 2011, with tops, bodysuits, leggings and tights for keeping warm in the cold weather.
I tried the retailer’s popular Heatgen Thermal Scoop Neck Top that’s racked up over 3,000 five-star ratings.
The first thing that impressed me was the soft inner lining.
It provides extra warm without feeling overbearing, and it’s still just as lightweight as other thermal tops.
Primark has a similar style, and the pair has gone viral for its cosy fleece lining.
The scoop neckline gives a stylish feel that looks like any other staple top, so it could be worn alone or paired with other layers.
It’s definitely one that I’d opt for day-to-day (although it would still work well for outdoor activities), and I’ll be teaming it with knitwear and jackets in the cold weather.
As for the price, it’s one of the most affordable options around, and its versatility means I’ll get so much wear out of it this winter.
Size: 6-22; Material: 64% acrylic, 28% viscose and 8% elastane; Colours: Cream, Navy, Black, Blackberry
Pour Moi Second Skin Thermal Long Sleeve Top
Pour Moi Second Skin Thermal Long Sleeve Top, £25
Pros: Stretchy, Close fit is super comfortable, flattering design, choice of seven colours, sparkly option for wearing as only layer
Cons: Thin material
Rating: 9/10
I was pleasantly surprised by Pour Moi’s thermals.
The long sleeved top is very thin, so I was expecting it to be of a lower quality to others I’ve tried.
I couldn’t have been more wrong, and I understand why the brand has named the base layer ‘second skin’.
The design is fitted but stretchy, and one of the most comfortable I’ve tried.
It hugged my figure in all the right places, and while I’ll be wearing it as a base, I was still impressed with how flattering the top is.
The scoop neckline makes it easy to layer up with other pieces, and I’ll be pairing it with jumpers and cardigans for everyday wear.
One of the seven colours has a glittered design, and I could see it being perfect for staying warm on winter evenings out.
I also tried the matching Pour Moi leggings, which had the same close, flattering fit that kept me warm all day.
Size: 8-22; Material: 56% Acrylic 37% Viscose 7% Elastane; Colours: Seven colours
Mountain Warehouse Merino Zip Neck Thermal Top
Mountain Warehouse Merino Zip Neck Thermal Top, £34.99 (was £59.99)
Pros: High-quality, made from merino wool, antibacterial material, zip-up neckline gives extra warmth, good range of colours
Cons: Expensive when not on sale, not as easy to layer as other options
Rating: 8/10
Mountain Warehouse’s large selection of women’s thermals are designed for outdoor activities, and I tried the Merino Zip Neck Top.
It’s made from 70% Merino wool, which is the best material for thermals as it’s naturally odour resistant (and doesn’t need to be washed as frequently as other fabrics).
The zip-up neckline is great for adding some extra warmth, although it means it’s not quite as easy to layer.
I really like the appearance of this top, plus it feels high-quality and warm without being restrictive.
It’s probably not one I would reach for much day-to-day, but I can see it being perfect for activities like skiing.
It’s on the expensive usually, but the Mountain Warehouse buy is currently reduced to £35.
Size: 6-24; Material: Merino wool 70%, Polyester 30%; Colours: Black, Teal, Navy, Grey, Purple
Uniqlo Heattech Ultra Warm Crew Neck T-Shirt
Uniqlo Heattech Ultra Warm Crew Neck T-Shirt, £24.90
Pros: High-quality material, cosy without being restrictive, good for layering
Cons: Not as flattering as other alternatives
Rating: 7.5/10
When it comes to fashion basics, Uniqlo is high-street royalty.
I put one of the retailer’s Heattech Long Sleeve Tops to the test, and I was seriously impressed with the quality for the price.
Firstly, the crew neck design makes it feel like an everyday basic, which is elevated by the thick, cosy material.
As it’s far from flimsy, the top is designed to hold its shape through every wash.
Its made with a moisture-wicking material, so you won’t feel sweaty even if you get too hot.
Ultra-fine fibres have also been used to help neutralise odour, and while it doesn’t feel quite as high-quality as those made with merino wool — it comes incredibly close.
Size: XXS-XXL; Material: 41% Acrylic, 37% Polyester, 18% Viscose, 4% Elastane; Colours: Grey, Black, Off-White
Mountain Warehouse Keep The Heat Thermal Vest Top
Mountain Warehouse Keep The Heat Thermal Vest Top, £11.49 (was £22.99)
Pros: Comfortable, great for layering, affordable, moisture-wicking
Cons: Not as warm as long sleeve options
Rating: 7.5/10
While Mountain Warehouse’s Keep The Heat vest obviously isn’t as cosy as long sleeve alternatives, it’s the perfect choice for layering.
The vest could be worn with just about any other clothing for added warmth, and the close fit does still offer plenty of insulation.
It’s also moisture-wicking for keeping fresh over long periods, so it would be a good choice for wearing with a fleece for outdoor activities.
One of the most affordable options around, the thermal vest costs less than £12 (as it’s currently 50% off in the sale).
Size: 4-28; Material: Acrylic 37%, Polyester 32%, Viscose 25%, Elastane 6%; Colours: Grey, Black
Where to buy thermal clothes
Thermal clothing can be bought from a range of stockists, including high-street retailers, supermarkets and Amazon.
If you’re looking for easy-to-wear base layers for everyday or lighter activities, places like Marks & Spencer and Uniqlo have several options that can be bought online or in-store.
Those searching for base layers for specialist activities may want to take a look at some of the retailer’s specialising in sport-related clothing.
Mountain Warehouse and Under Armour are some of the brands stocking a good selection of pieces.
Full list of stockists:
What is thermal clothing?
Thermals are an insulated base layer that can come in the form of leggings, tops and fleeces.
It works to keep users warm by trapping a layer of hot air close to the body, minimising the amount of heat that’s lost.
The clothing comes with a close fit to ensure the heat stays close to the body, and most base layers also come with moisture-wicking designs.
Moisture-wicking clothing draws sweat from the skin to the outer fabric where it evaporates, keeping the skin dry and heated.
Merino wool is often used in thermals, as the material is warm and odour-resistant.
Polyester and nylon are also commonly used, as both fabrics are quick-drying and moisture wicking.
How do thermals work?
Thermal layers work by insulating heat by trapping the warm air close to the skin.
Materials often used in the clothing (like Merino wool and polyester) create small air pockets that act as a barrier to prevent any heat loss from the insulation.
Body heat will naturally escape in the cold weather if there’s no barrier to keep it in, so the trapped layer of heat caused by thermals will slow the rate of the heat escaping.
For thermals to work as effectively as possible, the fabric needs to be moisture-wicking.
Sweat evaporates and therefore pulls heat away from the skin, which leads to use feeling cold.
Moisture-wicking materials instead draws the moisture away from the skin, keeping it dry and preventing the chill.
Do you wear thermals under clothes?
Yes, thermals are base layers and are therefore designed to be worn under clothes.
The clothing can only work to its full effect if it’s worn against the skin, so it needs to be worn as a first layer.
The moisture-wicking properties pull sweat away from the skin to keep you warm and dry, so if the thermal was worn over other items, the top layer would soak up the sweat.
Thermals are designed to be worn in the cold weather, so it’s unlikely that they would be needed as an only layer, but instead the leggings, tops or fleeces can be worn with further layers on top.
For more winter warmer’s, Argos has slashed 25% off a luxury thermal bedding set, and shoppers are saying they don’t need to turn their heating on with it.
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