Best Base Layers for Women of 2024

“There’s no such thing as bad weather, only unsuitable clothing,” said Alfred Wainwright in his 1973 book “Coast to Coast.” Surely, he had base layers in mind when contemplating clothing systems. The best base layers for women will keep you warm, dry, and comfortable, and you can wear them stand-alone or layered underneath a jacket or vest.

We began this guide by compiling a list of layers that would meet different conditions and preferences. We narrowed down our top picks and tested them in all types of environments, from the fickle storm days of the Pacific Northwest to the rugged San Juan mountains of Colorado.

Our testing grounds also included the high-elevation deserts of Utah and the forested mountains of western North Carolina. We selected natural fiber, synthetic, and blended-fabric layers and paid attention to some budget-friendly options. Our goal is to help you choose the best base layer for your needs.

Our top choice is the Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve, which is perfect for wearing alone or layering and has excellent wicking capability. The Tracksmith Fells Waffle Layer is our favorite midweight base layer for bitterly cold days, and the Oiselle Flyout Long Sleeve is our layer of choice in the super lightweight category. Baselayers often pair well with tights, and to see our favorite options, take a look at our Best Women’s Running Tights guide.

For more background information about the various base layers on the market and how we chose our winners, see our buying advice, testing methodology, and frequently asked questions below the picks.

Best Base Layers for Women

• Best Base Layer for Women: Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve
• Best Base Layer for Women — Runner-Up: Janji Repeat Merino Long Sleeve
• Best Base Layer for Women— Runner-Up: Paka Women’s Everyday Base Layer
• Best Midweight Base Layer for Women: Tracksmith Fells Waffle Layer
• Best Ultralight Base Layer for Women: Oiselle Flyout Long Sleeve
• Best Budget Base Layer for Women: Under Armour Women’s HeatGear Compression Long Sleeve
• Best Short Sleeve Base Layer for Women: Tracksmith Harrier Tee

Best Overall Base Layer for Women: Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve ($90)

Pros:

• Lightweight
• Wicks well
• Odor resistant

Cons:

• Expensive
• Easy to snag

The Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve has long been a staple in many runners’ chilly-weather arsenals and with good reason. It’s lightweight and not bulky, so you can easily layer it under heavier items in freezing weather, but it’s substantial enough to wear alone.

This base layer features Smartwool’s Core Spun technology, consisting of merino wool fibers wrapped around a nylon core. This adds durability to the material while keeping the comfort and wicking properties of ultra-soft merino next to your skin. The raglan cut on the sleeves means it won’t chafe your shoulders if you wear it under a hydration vest, and the merrow stitching down the sleeves is super smooth, reinforced, and very comfortable.

The high merino wool content means this layer won’t pick up an odor, and you can wash it less frequently, adding to its shelf life. Wool fibers naturally repel odor-causing bacteria, making them a great base layer material. This top also dries quickly, so rinsing it during multi-day fastpacking trips is no big deal.

Notably, one of our testers experienced a hydration bladder leak while running up Mount Leconte in the Great Smoky Mountains National Park in Tennessee, and this layer still kept her warm despite being soaked all down the back.

Finally, Smartwool uses ethically sourced and recycled wool to reduce its products’ environmental footprint. This layer is available in a variety of color choices and sizes and as a ¼-zip top if you want the option of additional venting.

Material: 88% merino wool, 12% nylon | Fit: Slim | Actual Weight: 5.3 ounces (150 grams)

Shop the Smartwool Women's Classic All-Season Merino Base Layer Long Sleeve

Best Base Layer for Women — Runner-Up: Janji Repeat Merino Long Sleeve ($88)

Pros:

• Highly breathable
• Thumbholes
• Odor resistant

Cons:

• Best for cool or transitional weather versus very cold

Choosing the best base layer for women was difficult, and the Janji Repeat Merino Long Sleeve scored high in many categories for most of our testers. This ultralight layer has a T-shirt-like fit and is a favorite for chilly and transitional weather. We found it to be a comfortable layer for runs that start cold but gradually heat up, as it isn’t overbearing in its warmth level. The thumb holes at the end of the sleeves offer extra protection over the hands on brisk mornings and also keep the sleeves from riding up when putting an extra layer on over top.

The merino in this shirt is Responsible Wool Standard (RWS)-certified, and the nylon is Bluesign-certified, meaning it is free from harmful chemicals and fabricated in a way that meets a high environmental standard. The blend of nylon and wool makes for a durable material that maintains all of wool’s moisture-wicking and odor-control properties. It is also quite breathable, and we typically wear it multiple times between washes.

We also love that Janji has a clearly stated environmental mission and donates 2% of every purchase to clean water programs around the world.

Material: 47% RWS-certified merino wool, 53% nylon | Fit: Relaxed | Actual Weight: 4.5 ounces (129 grams)

Shop the Janji Repeat Merino Long Sleeve

Best Base Layer for Women — Runner-Up: Paka Everyday Base Layer ($75)

Pros:

• Buttery soft
• Layers well

Cons:

• Not quite as warm as our top pick
• Loses shape with multiple wears

The Paka Women’s Everyday Base Layer also scored high among testers with its incredibly soft feel and T-shirt-like fit. This base layer is a blend of alpaca wool and Tencel, made from wood pulp and known for being both soft and durable. The top is very lightweight with a sort of body-skimming, almost liquid texture, but it offers solid warmth, especially for how light it is.

Testers scored it highly on fit, breathability, and drying time. We noticed that it loses its shape a bit after several wears, but this is easily resolved with a wash and hang dry. Its fit works great layered over a short-sleeve shirt, on its own, or underneath a jacket, and it’s proven its durability over many months and miles of wear.

We also love running gear that we can wear casually, and this top fits the bill. It became a regular in our rotation for casual wear in addition to being a functional piece of running gear.

We appreciate Paka’s transparency and sustainability practices. They ship their products in compostable packaging, and consumers can trace garments to the exact coordinates where the fiber for their item was sourced.

Material: 80% Tencel, 20% royal alpaca | Fit: Casual | Actual Weight: 4.9 ounces (139 grams)

Shop the Paka Everyday Base Layer

Best Mid-Weight Base Layer for Women: Tracksmith Fells Waffle Layer ($130)

Pros:

• Ideal for extra chilly or damp days
• Waffle design insulates, wicks, and breathes

Cons:

• Very expensive
• No thumbholes

The Tracksmith Fells Waffle Layer is inspired by British fell running, which is similar to cross-country and mountain running and is characterized by wet and wild weather and challenging, steep terrain. This midweight base layer is perfectly suited to such conditions and the typical shoulder season weather found across much of the United States. It features a blend of merino wool and recycled polyester, so it maintains the odor-resistance of wool and the durability of synthetic fibers.

As a midweight layer, this top is thicker and heavier than our top picks above. Nevertheless, the Fells Waffle Layer has a relaxed-fitting style and waffle texture, enhancing its breathability and wicking performance. The waffle texture also allows the layer to provide insulating warmth by trapping air against your skin.

Our testers found this to be the ideal extra-cozy layer while warming up for a track workout or on those gloomy fall days when the chilly air makes it hard to get out the door. Like most of our favorite base layers, this top transitions well between daily running and casual wear around town.

Finally, Tracksmith apparel generally tends to run small, but this layer fits true to size according to the brand’s size guide. We recommend taking measurements and using the guide to choose the best size.

Material: 54% merino, 46% recycled polyester | Fit: Relaxed | Actual Weight: 9.1 ounces (258 grams)

Shop the Tracksmith Fells Waffle Layer

Best Ultralight Base Layer for Women: Oiselle Flyout Long Sleeve ($82)

Pros:

• Thumbholes and watch windows
• Light and breathable
• Vegan

Cons:

• Not as warm as other favorites

When you want an ultralight base layer for those shoulder-season runs that are crisp but not super cold, the Oiselle Flyout Long Sleeve has a lot to offer. Oiselle uses its proprietary Flyout fabric with HoverFit technology, with the idea being that the material can hover above the skin, helping with heat and sweat transfer. This is not unlike the Tracksmith waffle design above but applied to a much thinner fabric. This layer fits loosely against our skin, wicks sweat, and breathes incredibly well. This top incorporates a synthetic blend fabric that’s not quite as odor-resistant as those that use natural fibers. However, it’s worth noting that the Flyout uses Bluesign-approved materials.

Oiselle is a brand that offers gear made specifically for active women’s bodies, and items are available in an inclusive range from size 2 to 26 (XS-3X). The raglan sleeve design helps to eliminate seams chafing around the arms and shoulders, and testers noted that this layer feels ultra-soft against their skin.

We love the thumb holes that kept the sleeves down and warmed our hands, and we also appreciate the watch window, which allows us to keep an eye on our splits and pace without having to roll up our sleeves. This shirt is perfect for a track workout where you start cold and warm up quickly but don’t want to stop and shed layers. Finally, while this is a great ultralight layer and offers a decent amount of warmth for its weight, it’s not as warm as our top picks from Smartwool, Janji, and Paka.

Material: 49% polyester, 49% Tencel, 2% spandex | Fit: Skin tight | Actual Weight: 3.8 ounces (109 grams)

Shop the Oiselle Flyout Long Sleeve

Best Budget Base Layer for Women: Under Armour Women’s HeatGear Compression Long Sleeve ($35)

Pros:

• Wicks well
• Great value
• Vegan

Cons:

• Not the most breathable
• It felt too tight in places on some testers

If you want a solid base layer that will keep you warm and doesn’t come with a hefty price tag, the Under Armour Women’s HeatGear Compression Long Sleeve is a great choice. It’s an approachable, readily available, and budget-friendly option, and this lightweight layer did not disappoint when it came to performance. It’s made with the brand’s HeatGear fabric, a four-way stretch material, and has flatlock seams that offer a chafe-free fit.

Notably, this is a compression top, and some people might not like the tightness of the fit. The science of using compression clothing for performance improvement is inconclusive, but many people like the support and feel of it, especially during longer runs where all parts of the body start to hurt by the end. If you’re not into the compression fit, consider sizing up.

Our team of testers noted that this layer wicked sweat well and was comfortable up to 55 or even 60 degrees Fahrenheit, though it wasn’t ideal for those warmer temperatures. They also noted that although this is a synthetic layer, it offered excellent odor resistance, making it a great value for shoulder season running.

Material: 87% polyester, 13% elastane | Fit: Compression | Actual Weight: 5.0 ounces (143 grams)

Shop the Under Armour Women's HeatGear Compression Long Sleeve

Best Short Sleeve Base Layer for Women: Tracksmith Harrier Tee ($90)

Pros:

• Soft
• Versatile year-round

Cons:

• Expensive
• Not size-inclusive

The Tracksmith Harrier Tee is a staple for year-round running, but we especially like it as a base layer during fickle shoulder season weather and colder months. This short-sleeve running tee has a loose, comfortable fit that allows airflow and a full range of movement while still layering well underneath a long-sleeve shirt or jacket. It’s soft and light without feeling thin and has just a little stretch so that it never feels restrictive.

This base layer features a blend of merino wool and nylon, and it features 37.5 Technology materials, which claim to remove heat from the body while it’s still in vapor form to help keep you cooler while running in hot weather. This technology essentially works the same as merino wool, wicking moisture away from the skin before it becomes droplets of sweat. Regardless, we agree that this tee is a versatile layer that performs well in just about any weather conditions.

Its natural fiber-blended fabric resists odor, can be worn multiple times between washes, and dries quickly. Although it has a hefty price tag, it’s proven to be a long-lasting piece of running gear that our testers keep reaching for day in and day out. As such, it’s arguably a worthwhile investment that will prove its value again and again over many seasons.

The Harrier Tee is fitted but not tight or restrictive, and it fits true to size according to Tracksmith’s guide. However, we’d love to see a broader range of size offerings from the brand. For example, this shirt fits chest measurements between 30 to 42 inches, while Oiselle’s Flyout Long Sleeve, by comparison, fits a range of 31 to 53 inches.

Material: 48% merino wool, 52% nylon | Fit: Fitted | Actual Weight: 3.5 ounces (101 grams)

Shop the Tracksmith Harrier Tee

Comparing the Best Base Layers for Women

BASE LAYER	PRICE	MATERIALS	WEIGHT
Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve	$90	88% merino wool, 12% nylon	Light
Janji Repeat Merino Long Sleeve	$88	47% merino wool, 53% nylon	Light
Paka Women’s Everyday Base Layer	$75	80% Tencel, 20% Royal alpaca	Light
Tracksmith Fells Waffle Layer	$130	54% merino, 46% recycled polyester	Medium
Oiselle Flyout Long Sleeve	$82	65% polyester, 32% Tencel, 3% spandex	Ultralight
Under Armour Women’s HeatGear Compression Long Sleeve	$35	87% polyester, 13% elastane	Light
Tracksmith Harrier Tee	$90	48% merino wool, 52% nylon	Light

Buying Advice: How to Choose Base Layers for Women

When trying to find the best running base layers for women, there are many details to consider, including where you’ll be running. Is the climate dry or humid? Will you likely sweat or stay dry? How cold will it be? Does the layer need to fit under several more layers for warmth, or will you wear it as a stand-alone layer?

All these factors come into play when choosing the right base for your run. Our team found that the Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve was the right mix of all the factors, making it our favorite overall base layer.

Fit

When considering fit, think about what you will wear on top of your base layer. A base layer can also be a standalone garment for some climates or transitional weather. Some of the layers we tested were perfect for chilly weather and had a looser fit for ease of motion and comfort. The Paka Women’s Everyday Base Layer has one of the softest and most comfortable everyday fits and layers well on extra-cold days.

Tight-fitting tops or compression layers, like the Under Armour Women’s HeatGear Compression Long Sleeve, can feel less bulky, which some runners prefer for both warmth and comfort. Additionally, compression layers may promote blood flow and oxygenation to muscles and can be used to support fatigued muscles.

Seam size and location are important. Many of the layers we tested featured a raglan-style cut to eliminate the seams around the shoulders and had specialty stitching in other places to reduce the possibility of chafing. The Janji Repeat Merino Long Sleeve combines merrow stitching and thumbholes that function well to keep layers comfortably in place on long runs and under hydration vests.

Material

Traditionally, many runners have turned to merino wool for their base layers. Merino wool is known for being insulating, even when wet, and for helping regulate temperature by controlling the rate of moisture evaporation from the skin. It is highly breathable due to the porosity of the fibers, and you can stay dry even as you sweat.

As far as warmth for the buck, merino will do a great job of keeping you insulated from colder temps. A lightweight merino or merino-blend base layer is an excellent option for cooler temperatures, while a mid- or heavyweight merino will keep you toasty in the coldest climates. The Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve has a very high merino content, meaning it keeps runners cozy in all conditions and offers warmth and breathability even while wet.

Regarding sustainability, runners will have to weigh where they stand on the ethical implications of using resources to raise livestock, the effect on climate change, and using animal products in clothing.

If you’re vegan or searching for more budget-friendly options for your base layer, look to synthetics. Typically, a polyester or polyester-blend base layer will excel at wicking and keeping you super dry. Synthetic base layers are available in a variety of fits, including compression. They often have a tighter fit than wool, which is excellent if you want to add layers on top for warmth or weather protection.

Because of their wicking capability and quick-drying attributes, synthetic layers will minimize chafing and keep you from overheating. Oiselle’s Flyout Long Sleeve is a high-performing base layer that checks the boxes for our vegan runners and those who prefer synthetic fabrics to wool.

Weight

Generally speaking, you’ll want to choose the layer that will best fit most of your running circumstances. Lightweight layers are best for moderate to cool temperatures and runs that might begin in chillier weather that warms up during the day. Midweight layers are effective for cold to frigid temps, especially when layered under a jacket.

One thing to consider is that the primary job of a base layer is to keep the wearer comfortable and dry. Additional warmth is almost always determined by what you wear on top of the base, including the outer layers. Finding the most comfortable and wicking base layer against your skin is paramount.

The Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve was a good weight for wearing on its own or with additional layers. Most layers tested for this buyer’s guide were lightweight or mid-weight options.

UPF Rating

UPF stands for ultraviolet protection factor, and some base layers carry a tag with a UPF rating for sun protection. The UPF rating refers to how much UV the fabric of the garment blocks. In general, a darker-colored fabric will offer more UV protection, as will a fabric with a tighter, denser weave.

Synthetic materials like polyester provide more protection than natural fibers like merino, and a looser fit offers more protection than an item stretched tightly across the skin. If your runs take you to environments that have you out in the open and exposed to the sun’s rays, or if you’re at a higher elevation, have sun-sensitive skin, or are taking medication that makes you vulnerable to the sun, a UPF rating may be important to consider. None of the base layers included in this guide have a UPF rating, but there are great options to consider in our Best Sun Shirts for Running guide.

Breathability

Arguably, breathability is one of the most important aspects of a base layer. There’s nothing worse than being drenched in sweat or precipitation and feeling like you can’t escape it. Material, weight, and openness of the weave all contribute to a layer’s breathability.

Lightweight merino and synthetic base layers tend to be more breathable than heavier ones. Merino, in particular, is known for its thermo-regulating properties, as it has superior wicking capability while also keeping you warm even when wet. The Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve is our favorite warm and breathable merino layer, while the HoverFit technology of the Oiselle Flyout Long Sleeve made it score high on the breathability scale among synthetic layers.

Odor Prevention

Natural fiber is the clear winner in stink prevention. The wicking nature of natural fiber, like merino wool, contributes to its odor resistance. Because it stays dry, allowing water to evaporate before it soaks the material, there’s less chance for odor-causing bacteria to flourish, thus less funkiness caused by microbes.

Layers with natural fibers also don’t need to be washed as often, and any time you can get more than one run from a layer is a win. Our testers could run in Smartwool’s Women’s Classic All-Season Merino Base Layer Long Sleeve, Janji Repeat Merino Long Sleeve, and the Paka Women’s Everyday Base Layer over several back-to-back outings with nary a wash or rinse.

Durability

Many of the base layers on the market require shelling out a fair bit of dough, so of course, we want these items to last for as long as possible. Another plus for merino or merino blends is that they reduce odors, so you won’t need to wash them as much. Less frequent washing can extend a garment’s shelf life. We recommend air-drying base layers, especially wool ones, which should never be put in the dryer, to help extend their lifespan as well.

Several team members have owned Janji Repeat Merino Long Sleeve for multiple seasons and have been impressed with its long-term durability. That said, we have yet to experience any notable durability issues with any of the layers included in this guide, which is why we selected them as our top picks! Having to replace items frequently has an environmental impact, but more on that below.

Warmth

When choosing the best base layers for women, consider climate and environment. Ideally, we want to select the lightest and most functional base layer for that day’s effort. Running base layers are usually ultralight or lightweight for cool to chilly weather or midweight for cold and extreme weather.

A mid-insulating layer like a light puffy or top shell, such as a windbreaker or waterproof rain jacket, provides additional warmth. The Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve is a classic base layer that works well in chilly temperatures but can be worn under extra layers as temperatures drop.

Styles

The world of the best base layers for women offers many styles to choose from. Some are available in short-sleeve lengths as well as long sleeves, like Tracksmith’s Harrier Tee and Harrier Long Sleeve. The Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve is available in a crew form and a quarter-zip option. Several base layers on the market also have hoods.

Within this testing, the Paka Women’s Everyday Base Layer ranked high in the style category, with runners commenting that the layer looks so nice and dries so quickly that it easily goes from run to town. It’s likely to double as a non-running item in many closets as well.

Sustainability

Many runners tend to be relatively conscious consumers, so considering sustainability is a great way to narrow down choices when making an investment. Some issues to think about when choosing a garment are the manufacturer’s factory emissions, including gas emissions and anything that may eventually end up in a water source, whether companies compensate producers and plant workers fairly, how they source raw materials, and how the company as a whole gives back to our community and our world.

In the group of products we chose, almost all of the merino used was ethically sourced and certified by a third-party organization. Depending on animal conditions, merino can be considered eco-friendly as it consists of proteins and amino acids and eventually naturally breaks down in water and soil.

We are also impressed by companies using recycled packaging. Smartwool and Janji stood out in this area. Paka took it one step further with their Paka Women’s Everyday Base Layer by using compostable packaging and a system that allows one to trace the fibers in their garment back to their source via their website.

Why Trust Us

We tested base layers from more than ten different brands for this guide. Women from all over the country, including Colorado, Utah, Oregon, Tennessee, and North Carolina, put these layers through their paces in a variety of environments, elevations, and weather conditions. We tackled the trails, ran roads, and crushed some gravel.

We used the base layers in colder climates and some warmer weather ones to test breathability and wicking capabilities. We referred to some of our old familiar products that we know and love, and we threw some newcomers and outliers into the mix to narrow our list down to the best base layers for women.

Our goal is to find the best products on the market so that you can run your best. We routinely update our buyer’s guides based on ongoing testing and research by our authors and editorial team. We also seek out expert advice from designers, athletes, and coaches. For the buying advice and FAQ sections in this article, we consulted Polartec’s North America Product Manager, Michael Cattanach, as well as Monica Broder of Weft Design Studio.

Frequently Asked Questions About Base Layers for Women

What is the best type of base layer for running?

The best base layer for women will be the lightest and most comfortable for a specific situation, and that will be dependent on a runner’s climate and environment. Layers with merino-blend fabric have been far and away the frontrunner among the base layers we’ve tested, but several synthetic blends also offer warmth and strong wicking performance. Our team loved the Under Armour Women’s HeatGear Compression Long Sleeve and named it the best budget running base layer for women.

What makes merino wool a good base layer material?

Many of the best base layers for women include merino wool. That’s because merino wool allows water vapor from your skin to evaporate before it turns into water droplets. This comes from the porosity of the fibers and helps them stay dry while wicking moisture away from your skin.

“I’m a big fan of merino for most activities,” said Monica Broder, Founder and Lead Designer at Weft Design Studio. “It’s naturally temperature regulating, breathable, and anti-bacterial, so it can often be worn multiple times between washes.”

Merino wool, such as that used in the Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve, insulates even when wet and helps regulate temperature by controlling the evaporation rate. It is odor-resistant and quick-drying, so base layers made with merino wool stay fresh longer between washes. Washing less frequently adds to the shelf life of the layer.

What are the best types of base layers for extreme cold?

The tricky thing about running in the cold is that runners generate heat while they’re moving. Too much heat leads to sweat, which soaks into layers and causes cold sensations.

For extremely cold conditions, choosing a heavier-weight thermal base layer that will hold more warmth might be necessary. Generally, midweight base layers, especially if they include wool or a wool blend, like the Tracksmith Fells Waffle Layer, will get most runners through most conditions.

Remember, the main job of a base layer is to move moisture away from your skin without getting wet, so a thinner layer that wicks effectively will be better than, say, a cotton sweatshirt that will absorb sweat and then feel cold.

Michael Cattanach of Polartec North America explains, “We talk about moisture management all the time, but what it really means is keeping your sweat away from the body so that in cold conditions, you do not have sweat against the skin. It’s true that wool does this really well, but it also needs to be built into a fabric construction that can move moisture away from the body by means of wicking. 

“Synthetic materials can be knitted to wick moisture very effectively, but a synthetic-only garment overloaded with moisture can start to have a cooling effect. The addition of an engineered percentage of wool can add the benefit of feeling warmer. Indeed, the science would tell you that wool can absorb about 30% of its weight in moisture before it starts to feel cold against the skin.” 

Are there warmth ratings for base layers?

Matt Cattanach of Polartec explains, “We can measure warmth by means of Rct, the big R standing for the Resistance to cold temperature. The warmth of a material is related to its thickness.”

Base layers can be lightweight, ideal for both cool and cold weather, midweight for cold to freezing weather, or thermal for the most frigid conditions. Adding extra layers on top of your base layer, such as a jacket or vest, will increase warmth.

However, choosing the lightest wicking layer for the conditions will keep you from sweating through your layers. Again, Matt Cattanach emphasizes moisture management for running and other high-output activities: “If you are using a lot of energy, burning lots of calories, generating lots of watts, and sweating a lot, then you want to concentrate on a base layer that prioritizes moisture management.” You can always add a running vest or windbreaker on top for added warmth. 

Our testing team recommends a lightweight base layer made of wool, like the Janji Repeat Merino Long Sleeve, as a great starting point.

Call for Comments

• What’s your favorite base layer?
• How do you like to layer for running in cold weather?

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