AS the first real chill of winter sets in, now is the time to rethink your layering game—and the best thermals for women can make all the difference.
Whether you’re braving the morning commute or planning a weekend outdoors, a high-quality base layer is essential for staying warm and comfortable as temperatures drop.
With Black Friday fast approaching, it’s also the perfect moment to snap up deals on top-rated thermals from trusted stockists like M&S, Amazon, and Uniqlo.
We’ve rigorously tested the latest options, from moisture-wicking merino wool to innovative tech fabrics, to help you find the best base layers for every occasion – so you can stay cosy, stylish, and ready for whatever winter brings.
Best thermals for women at a glance
How we test
To make sure only the best thermals make the cut, I put every pair of leggings, tops, and fleeces through their paces over several weeks — both indoors and out.
Each piece was worn as a base layer under different outfits — from brisk morning walks to chilly evenings on the sofa — so I could gauge real-world comfort and warmth.
I paid close attention to quality, fit, style, the range of sizes and colours on offer, and value for money.
Above all, I wanted to see which thermals truly locked in heat without feeling bulky or restrictive.
And, as always, I’ve compared these to the best leggings for women to ensure you’re getting advice you can trust.
The best thermals for women, tried and tested
1. Acai Thermal Altitude Leggings
Acai Thermal Altitude Leggings, £79
Pros: Incredibly comfortable, very warm, durable, high waist, flattering fit, phone pocket, zipped waistband pocket
Cons: None
Rating: 10/10
The Acai Thermal Altitude Leggings are my top pick for winter.
These are some of the most comfortable leggings I’ve worn — super soft on the legs, with a high waist and a wide waistband that stays put.
The fit is snug without feeling restrictive, giving supportive compression and a flattering silhouette.
With a 1.1 tog rating, they are seriously warm yet the fabric stays lightweight and durable, so they work for frosty walks, long commutes or quick errands.
Practical touches seal the deal, including a deep side pocket that fits my phone and a zipped pocket in the waistband for keys and cards.
Available in sizes 8 to 18 and four on-trend shades — Black, Mulberry, Deep Navy, and Petrol Blue — they deliver style and substance all season.
Sizes: 8 – 18; Material: 86% polyester and 14% Spandex; Colours: Black, mulberry, deep navy and petrol blue
2. Acai Women’s Thermal Skinny Outdoor Trousers
Acai Women’s Thermal Skinny Outdoor Trousers, £99
Pros: Flattering skinny fit, looks like jeans, super warm fleece lining, water-resistant, plenty of pockets, great stretch
Cons: None
Rating: 10/10
When the temperature drops, the Acai Women’s Thermal Skinny Outdoor Trousers are an easy win for warmth and polish.
They fit like your favourite leggings but look like skinny jeans, with a zip, belt loops and proper pockets, including riveted fronts, a patch pocket and a zipped pocket at the back.
The thermal fleece lining is cosy on cold walks and morning commutes, yet breathable enough that you will not overheat when the sun comes out.
A water-resistant, stretchy fabric blend — 91% polyester and 9% spandex — moves with you and shrugs off light showers, and the close fit slips neatly into wellies.
They are just as at home on a hike or a dog walk as they are for popping into town.
Material: 91% polyester and 9% spandex, Size: 10 – 16, Colours: Purple and black
3. M&S Heatgen Thermal Scoop Neck Top
M&S Heatgen Thermal Scoop Neck Top, £17
Pros: Super-soft lining, comfortable stretch, stylish scoop neck, affordable, versatile for layering or wearing alone, four colour options
Cons: May be too thick for some fitted outfits
Rating: 9/10
After a thermal top that looks good and actually keeps you warm? The M&S Heatgen Thermal Scoop Neck Top is a winner for everyday wear.
The inner lining is unbelievably soft against the skin, and it delivers proper warmth without bulky layers.
The stretch fit sits smoothly under chunky knits, blazers and coats, while the scoop neckline feels sleek enough to wear on its own for a simple, polished look.
It holds its shape nicely through repeated washes, so it stays looking fresh all season.
Some may find it a touch thick under very fitted pieces, but for day-to-day layering, it is spot on.
Available in sizes 6 to 22 and four classic colours (Cream, Navy, Black, Blackberry), it is also great value for money, especially during the sale season.
Size: 6-22; Material: 64% acrylic, 28% viscose and 8% elastane; Colours: Cream, Navy, Black, Blackberry
4. Helly Hansen Women’s Verglas Tur Pants
Helly Hansen Women’s Verglas Tur Pants, £126
Pros: Adjustable fit, ventilation zips for temperature control, multiple practical pockets, RECCO® avalanche safety, durable and stretchy construction
Cons: Premium price
Rating: 9/10
The Helly Hansen Women’s Verglas Tur Pants are built for big days outside, and they deliver where it counts.
You get a personalised fit thanks to the adjustable waist and hem, plus practical storage with open hand pockets and zippered thigh pockets for passes, snacks and your phone.
The fabric is stretchy, durable, and water-resistant, so it moves with you and shrugs off flurries on hikes and mountain trips alike.
If you warm up, discreet thigh vents boost airflow to help you cool down fast.
Available in sizes XS to XL and in Trooper grey, Lav Green and Ebony, they are comfortable, hard-wearing and smart enough for après.
The price is premium, but the adjustability, ventilation and all-weather performance make them a savvy buy.
Material: 67% cotton and 33% polyester, 94% polyamide and 6% elastane, Size: XS, S, M, L and XL, Colours: Trooper (grey), lav green and ebony
5. TOG24 Silsden Women’s Waterproof Trousers
TOG24 Silsden Women’s Waterproof Trousers, £49
Pros: Warm, fully waterproof, windproof, zipped pockets, shaped knees for easy movement, lightweight
Cons: Not close-fitting at the ankle
Rating: 9/10
Ready for rain, wind, and everything in between, the TOG24 Silsden Women’s Waterproof Trousers are a solid winter pick.
They keep you warm and dry with a 5K waterproof rating, a windproof woven polyester outer and a cosy thermal lining that’s ideal for wet dog walks or soggy school runs.
I love the practical touches: two deep zipped front pockets and a secure back pocket keep your bits safe, even in muddy fields.
Darts at the knees give you easy movement and the lightweight cut tucks neatly into boots or wellies.
The ankle isn’t adjustable, so it doesn’t sit tight, but the shaped fit still looks smart and feels comfy all year.
Available in UK sizes 8 to 18 in classic black, these trousers are a dependable choice when the forecast looks grim.
Material: 100% polyester; Size: UK 8 – 18; Colours: Black
6. Pour Moi Second Skin Thermal Long Sleeve Top
Pour Moi Second Skin Thermal Long Sleeve Top, £25
Pros: Incredibly comfortable, stretchy, flattering fit, wide choice of colours (including sparkly options), perfect for layering or wearing alone
Cons: Thin material (but still impressively warm)
Rating: 9/10
A thermal top that feels light but keeps you cosy, the Pour Moi Second Skin Thermal Long Sleeve Top is a strong pick.
The fabric is ultra-thin yet surprisingly warm, made from a heat‑generating, super-soft stretch material that sits comfortably under layers.
The close, body‑hugging fit earns the “second skin” name, flattering without feeling tight, and the scoop neckline slips neatly under jumpers, cardigans and coats.
There are seven colours to choose from, including sparkly options such as Glitter Black if you want something you can wear solo on a night out.
The only watch‑out is the thinness, so it shines as a base layer.
Pair it with the matching thermal leggings for a coordinated set that layers easily.
Size: 8-22; Material: 56% Acrylic 37% Viscose 7% Elastane; Colours: Seven colours
7. Magic Bodyfashion Stay Warm Shaping Thermal Leggings
Magic Bodyfashion Stay Warm Shaping Thermal Leggings, £41
Pros: Velvety soft, close-fitting, very comfortable, tummy-holding wide waistband, flattering shaping, impressively warm
Cons: Premium price, can be a squeeze to get on at first
Rating: 8/10
Magic Bodyfashion Stay Warm Shaping Thermal Leggings deliver warmth and a smoothing fit.
Velvety soft inside and out, they feel like a second skin the moment they are on.
The high elastane content hugs your figure in all the right places, offering support that never digs in.
I did have to wriggle the waistband over my hips at first, but once settled, it stayed put with no rolling, holding the tummy and smoothing the silhouette.
Despite their lightweight feel, they are surprisingly warm and perfect under dresses, skirts, or an oversized knit.
The wide waistband is the hero for all-day comfort and gentle shaping.
The price is on the premium side, but the comfort and sculpting are worth it.
Sizes: S – XXL; Material: 89% polyester and 11% elastane; Colours: Black
8. Mountain Warehouse Merino Zip Neck Thermal Top
Mountain Warehouse Merino Zip Neck Thermal Top, £34.99
Pros: High Merino wool content for warmth, naturally antibacterial and odour-resistant, adjustable zip neck, lightweight and breathable, great colour selection
Cons: Can be pricey at full price, not the sleekest for layering under very fitted pieces
Rating: 8/10
Looking for a base layer that actually keeps you warm on icy days? The Mountain Warehouse Merino Zip Neck Thermal Top earns its spot in the kit bag.
The merino-rich blend is naturally antibacterial and odour-resistant, so it stays fresh for longer and feels breathable as you move.
The zip neck is handy for locking in heat when the wind bites, then opening up for a quick cool down after a hike or ski run.
It is lightweight, non‑itchy and slim enough to slip under knits or a waterproof.
It is not the sleekest under very fitted pieces, but the quality and comfort make up for it.
Full price can be punchy, so keep an eye out for sales where it often drops to around £35.
Size: 6-24; Material: Merino wool 70%, Polyester 30%; Colours: Black, Teal, Navy, Grey, Purple
9. Uniqlo Heattech Ultra Warm Crew Neck T-Shirt
Uniqlo Heattech Ultra Warm Crew Neck T-Shirt, £24.90
Pros: Excellent value, ultra-warm, moisture-wicking, odour-neutralising, holds shape, easy to layer, sustainable materials
Cons: Not as flattering as some alternatives, not pure merino wool
Rating: 7.5/10
If you’re on the hunt for a warm layer at a great price, the Uniqlo Heattech Ultra Warm Crew Neck T-Shirt is a standout.
This is the warmest Heattech in the range, with a plush interior that feels cosy without bulk.
The fabric is soft and stretchy, designed to trap heat while wicking away moisture, so you stay warm without feeling clammy.
The crew neck cut works as an everyday basic and layers neatly under jumpers, cardigans, or a shacket.
It also holds its shape after repeated washes, and the ultra-fine fibres help neutralise odour for all-day freshness.
It is not the most figure-flattering option, but the comfort and performance are hard to beat for the price.
Size: XXS-XXL; Material: 41% Acrylic, 37% Polyester, 18% Viscose, 4% Elastane; Colours: Grey, Black, Off-White
10. Mountain Warehouse Keep The Heat Thermal Vest Top
Mountain Warehouse Keep The Heat Thermal Vest Top, £12.99
Pros: Comfortable, moisture-wicking, great for layering, affordable (often under £12 in sales), wide size range (4–28), classic colours
Cons: Not as warm as long-sleeve options
Rating: 7.5/10
The Mountain Warehouse Keep The Heat Thermal Vest Top is a smart, budget-friendly pick.
The close, streamlined fit slips easily under jumpers, fleeces or even a dress, giving your core extra insulation without bulk or bunching.
The fabric is soft, stretchy and moisture-wicking, so you stay comfortable on brisk walks, busy commutes and everything in between.
It is lightweight and quick-drying, which makes it handy for active days outdoors or travel.
You get an inclusive size range from 4 to 28 and two easy-to-match colours, Grey and Black.
It will not be as toasty as a long sleeve, but as a layering base for changeable weather, it earns a place in any wardrobe.
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 offer several options available online or in-store.
Those searching for base layers for specialist activities may want to take a look at retailers specialising in sportswear.
Mountain Warehouse and Under Armour are some of the brands stocking a good selection of pieces.
Full list of stockists:
What is thermal clothing?
Insulated base layers that can come in the form of leggings, tops and fleeces.
It keeps users warm by trapping a layer of hot air close to the body, minimising heat loss.
The clothing features a close fit to keep heat close to the body, and most base layers also feature moisture-wicking designs.
Moisture-wicking clothing draws sweat from the skin to the outer fabric, where it evaporates, keeping the skin dry and cool.
Merino wool is often used in thermals because it 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 insulate by trapping warm air close to the skin.
Materials often used in clothing (such as Merino wool and polyester) create small air pockets that act as barriers, preventing heat loss from the insulation.
Body heat will naturally escape in 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 heat escaping.
For the layers to work as effectively as possible, the fabric needs to be moisture-wicking.
Sweat evaporates, pulling heat away from the skin and causing the user to feel cold.
Moisture-wicking materials instead draw 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.
They’re designed to be worn in cold weather, so it’s unlikely they would be needed as the only layer; instead, leggings, tops, or fleeces can be worn with further layers on top.
For more winter warmers, Argos has slashed 25% off a luxury fleece bedding set, and shoppers are saying they don’t need to turn their heating on with it.
