Best Winter Running Jackets of 2024 – iRunFar

Having the right jacket for the conditions will keep you warm, dry, and running outside all winter. Photo: iRunFar/Eszter Horanyi

Just because winter arrives, bringing with it cold temperatures, precipitation, and shorter days, doesn’t mean we runners stop doing our thing. Choosing the best winter running jacket can make the downsides of winter more bearable, comfortable, and safe so that we can enjoy the upsides of the season. While sometimes we may retreat to the comfort of a treadmill or other indoor cross-training options during the coldest and nastiest days, the proper clothing can keep us outside and running in the fresh air.

To help you navigate the often complex and confusing world of winter running jackets, we searched the running and Nordic skiing worlds for the best options available. Our testing of nearly two dozen jackets can help you take the guesswork out of choosing the right jacket. Some of the jackets in this guide have been favorites of iRunFar team members for years, and others are relatively new to our closets. Whether you’re looking for extra insulation for those chillier-than-usual runs, a jacket that you can stuff into a pack on cold mountain runs for extra safety, or one that will keep you running in the coldest conditions, our guide has you covered. If you’re looking for an insulated jacket for those cold runs, consider our top pick, the Montane Fireball Nano Hooded Jacket. We found the La Sportiva Koro Jacket an excellent option for days when a fully insulated jacket was too much, but we needed more than a windbreaker. When we were just looking for an extra insulating layer, we turned to the Patagonia R1 Daily Jacket.

For more background information about how we put together this guide, see our buying advice, testing methodology, and frequently asked questions below the picks.

Best Winter Running Jackets

Hybrid jackets, including the La Sportiva Koro Jacket, combine breathability and warmth for cold, but not frigid, runs. Photo: iRunFar/Eszter Horanyi

Pros:

• Effective body mapping insulation
• Highly compressible

Cons:

• Expensive
• Runs a bit small

When temperatures drop below freezing, a lightweight insulated jacket like the Montane Fireball Nano Hooded Jacket is your friend. Whether you live in a cold climate where you’re regularly running in the negatives or your runs take you high in the mountains where temperatures can drop instantly, this incredibly versatile jacket will keep you warm. Our team loved it so much that we named it our top lightweight insulated pick in our best running jackets guide. The jacket uses Dynamic Eco synthetic insulation placed only around the core of the jacket. The sleeves and the hood are uninsulated, which improves the overall breathability of the jacket and lowers its weight. The outer shell features a blend of the brand’s Featherlite Air nylon and polyurethane, and we found it to block wind effectively. The iRunFar team loves hybrid jackets like this one because of their versatility. A fully insulated jacket can be too much unless you’re running in the coldest temperatures, but these strategically insulated jackets are ideal for situations where a windbreaker isn’t enough.

There are several adjustment points on this jacket, including the hem. Elastic on the cuffs seal in heat and keep the sleeves in place. There are two zip hand pockets for smaller items that double as a stuff sack if you need to store the jacket. The hood fits relatively tightly over the head and will fit over a smaller hat. For a synthetic jacket, we found this one to be highly compressible, and we could carry it in a running vest if we needed to.

The brand describes the fit as trim and close-fitting, but we found that the jacket simply ran a little bit small, especially if we wanted to put more than one layer underneath it.

We feature the Montane Fireball Nano Hooded Jacket in our best insulated jackets for running and best mountain running gear guides.

Weight: 7.9 ounces (224 grams) | Shell material: 90% Featherlite Air nylon, 10% Polyurethane | Insulation material: Recycled 40 grams/meter2 Dynamic Eco Insulation

Shop the Montane Fireball Nano Hooded Jacket

Pros:

• Lightweight for the warmth
• Variety of sizing options

Cons:

• Too much jacket for all but the coldest conditions

A fully insulated jacket is too warm unless you’re running in truly arctic conditions, but we still turn to The North Face ThermoBall Eco Hoodie 2.0 as the jacket we carry as our just-in-case layer for long adventure runs in cold conditions. It’s been a go-to safety option for iRunFar’s Editor-in-Chief Meghan Hicks for years for shoulder-season outings that start cold and require a warm layer in case something goes wrong. This jacket is made of 100% recycled materials and has a PFC-free DWR finish to repel light sprinkles. It uses recycled ThermoBall Eco polyester insulation. The quilted pattern keeps the insulation in place and prevents it from bunching up. As a long-time team favorite, this jacket has earned a spot in our best running jackets guide and our best insulated jackets guide.

Unlike many other jackets in this guide, the The North Face ThermoBall Eco Hoodie 2.0 has a fully insulated hood, which adds a significant amount of warmth. There are three zip pockets: two hands and one chest. The hand pockets serve as a stuff sack for the jacket, compressing it quite small to fit into most medium-sized running vests.

We found that the women’s version of this jacket has a slim cut compared to many others. It might be worth sizing up if you’re planning on wearing multiple layers underneath.

Shell material: 20-denier 38-gram/meter² 100%-recycled nylon with a PFC-free DWR finish | Insulation material: 11-gram/foot² ThermoBall Eco 100% post-consumer recycled polyester

Shop the Women’s The North Face ThermoBall Eco Hoodie 2.0Shop the Men’s The North Face ThermoBall Eco Hoodie 2.0

Pros:

Cons:

The arrival of winter and cold temperatures doesn’t mean that runners have to slow down, and the Patagonia Nano-Air Light Hybrid Hoody is an outstanding jacket option for staying warm and outside when the mercury dips. This jacket is strategically insulated in specific areas to provide protection where needed and allow venting in areas of the body that run hot. The synthetic insulation won’t lose its insulating properties when wet, whether from sweat or a drizzle, so the jacket is perfect for faster runs where you might build up some perspiration. The polyester shell over the insulation is breathable to allow water vapor to escape, and the R1 knit paneling on the rest of the jacket is also highly breathable. A spacious hood is easy to get on and off, and two zip pockets provide storage and a warm place to put chilly hands. All these features led us to include this jacket in our best running jackets and best insulated jackets guides.

We started testing this jacket in the fall of 2022, and it quickly became our go-to jacket for winter runs. Shortly after, it found its way into our best cold weather running gear guide as our favorite winter jacket. As outlined above, the jacket hits a perfect balance of insulation and breathability in the correct spots. It came in handy, particularly when facing a headwind, as the boosted insulation on the chest helped keep the core cozy. Meanwhile, the R1 back panel does an excellent job of wicking moisture.

Patagonia has always been a leader in the outdoor industry in terms of environmental considerations and practices. Patagonia manufactures this jacket in a Fair Trade Certified factory, and the company is part of the 1% for the Planet program, donating a percentage of its profits to environmental organizations. To make the jacket more environmentally friendly, Patagonia has used a perfluoride compound (PFC)-free durable water repellent (DWR) coating on the 100%-recycled polyester shell to make the jacket water resistant. The insulation is 93%-recycled polyester.

Weight: 11.8 ounces (335 grams) | Shell material: 100% recycled polyester ripstop with a PFC-free DWR finish | Insulation material: 93% recycled 40-gram FullRange polyester

Shop the Women’s Patagonia Nano-Air Light Hybrid HoodyShop the Men’s Patagonia Nano-Air Light Hybrid Hoody

Pros:

• Reasonably priced
• Excellent insulation on the chest and good stretch
• Can be worn as your outer layer or underneath a shell

Cons:

Can you tell we’re suckers for the hybrid jackets? There’s definitely a reason for it. Staying dry during a cold-weather run while wearing a jacket is important, and the breathability of the La Sportiva Koro Jkt makes it stand out from the rest. La Sportiva designed this hybrid insulated jacket to excel when working hard on your cold winter runs. It is made of entirely recycled materials, and the insulation on the front is a blend of Primaloft Thermoplume insulation and 100% recycled polyester. The insulation retains its warming properties even when damp. The rest of the jacket, including the hood, is a stretchy and breathable fabric. The PFC-free DWR coating provides water resistance for light precipitation. The jacket has two outer pockets to protect cold hands and two internal pockets for storing smaller items securely.

Like the Patagonia Nano-Air Light Hybrid Hoody above, this jacket hits the sweet spot of insulation and breathability in the correct places and has become a jacket we continually find ourselves reaching for when we head out the door in the winter. It was our experience that the La Sportiva Koro Jkt did a bit better than the Patagonia jacket when wintry precipitation was falling. So, if you contend with a bit of a wetter winter, this jacket is probably the better choice. It is featured in our best running jackets and best insulated jackets for running guides.

Weight: 12.6 ounces (358 grams) | Shell material: Polyamide and elastane | Insulation material: Primaloft ThermoPlume; 100% recycled polyester

Shop the Women’s La Sportiva Koro JktShop the Men’s La Sportiva Koro Jkt

Pros:

• Fits over a pack or waistbelt
• Quiet fabric
• Good water resistance

Cons:

• More expensive than other windbreakers

Windbreakers are perfect for cutting the cold wind on a winter day and creating a warm microclimate next to your skin by trapping heat while releasing water vapor so you don’t get clammy and wet. The Black Diamond Distance Wind Shell is a long-time favorite of iRunFar testers for its minimal weight and weather resistance. While many of the wind jackets we’ve tested over the years will repel some moisture, this jacket consistently kept us the driest for the longest. The 15-denier ripstop nylon is plenty breathable and very lightweight. It is also quiet and not as shiny and technical-looking as many other windbreakers, ideal for those who want to wear it to a post-run coffee.

The fit is slim but relatively roomy and fits over a pack or waistbelt. This can keep your items within the warm microclimate between your body and jacket and keep your snacks and water from freezing. The hood fits easily over a winter beanie, a headlamp, or a ponytail, and the elastic on the cuffs works to seal in heat. For storage, a chest pocket will fit several small items and doubles as a stow pocket for the jacket when you don’t need it.

This jacket was one of our favorites in our best running windbreaker jackets guide.

Weight: 3.6 ounces (102 grams) | Shell material: 15-denier ripstop nylon

Shop the Women’s Black Diamond Distance Wind ShellShop the Men’s Black Diamond Distance Wind Shell

Pros: 

• Lightweight
• Protective hood

Cons:

While some of our testers lament that the Outdoor Research Helium Rain Ultralight Jacket can feel a bit warm and muggy when running in warm and wet conditions, we’ve found that it excels when things get colder. As a 2.5-layer jacket, it has an outer layer with a DWR coating, an inner waterproof layer, and a coating on the inside to protect the fabric from sweat and body oils. The outer layer is made of 30-denier nylon, while the inner is a Pertex Shield waterproof membrane. This combination makes for an incredibly lightweight jacket that performs in wet conditions. The seams are sealed, and the hem and the hood are adjustable to make it easy to dial in the fit.

We found the fit of this jacket to be on the boxy side, so it was easy to wear extra layers underneath. The fabric doesn’t have a lot of stretch, so if you want to layer up underneath or are between sizes, you might want to consider sizing up. The water-resistant zipper is a bit finicky because of its small size, but if you avoid tugging on it, it should last for a long time. Outdoor Research also offers a 100% satisfaction guarantee, so if the zipper breaks, you can send it back for repair.

The hood is spacious and provides plenty of space for wearing a beanie or hat. It’s adjustable with a bungie in the back so that you can secure it if the wind picks up. Whether you’re running in cold and rainy conditions or a wet snowstorm, this jacket will keep your inner insulating layers dry so that you can stay warm.

We included this jacket in our best running rain jackets and best cold weather running gear guides.

Weight: 6.3 ounces (178 grams) | Shell material: Waterproof Pertex Shield

Shop the Women’s Outdoor Research Helium Rain Ultralight JacketShop the Men’s Outdoor Research Helium Rain Ultralight Jacket

Pros:

• Excellent value
• Stuffs into its own pocket for easy storage and carrying

Cons:

When you want an insulated jacket that will keep you warm on your cold-weather runs but don’t want to break the bank, the Decathlon Forclaz MT100 Hooded Synthetic Jacket is a great option. Made for running in sub-freezing temperatures, it’s also a great budget option to wear as an everyday insulated jacket for the rest of your life activities. It is the best budget option in our best insulated jackets for running guide. The 20-denier polyamide shell is water-resistant and durable, and the insulation is made of recycled polyester.

A drawstring on the hem adds fit adjustability, and the insulated hood provides extra warmth when needed. Two hand pockets provide enough storage for small items, and the jacket easily stuffs away into one of them.

This jacket runs small, so check the sizing chart before purchasing, and don’t be afraid to size up, especially if you plan on wearing more than one layer underneath it.

Weight: 13 ounces (370 grams) | Shell material: 20-denier polyamide | Insulation material: Recycled polyester

Shop the Women’s Decathlon Forclaz MT100 Hooded Synthetic JacketShop the Men’s Decathlon Forclaz MT100 Hooded Synthetic Jacket

Pros:

• Soft and comfortable
• Surprisingly warm

Cons:

For many of us, winter runs only require one additional insulating layer beyond what we’re used to in order to stay warm, and the Patagonia R1 Daily Jacket feels like the Goldilocks thickness for runs that are cold but not that cold. Fleece and fleece-like layers have come a long way in the past decade, and this jacket has the soft feel of traditional fleece without the bulk often associated with the fabric. In fact, it was the softness of this jacket that set it apart from other insulating layers. It’s quite stretchy and made of 94% recycled polyester, staying true to the brand’s commitment to using environmentally friendly manufacturing options whenever possible.

Patagonia’s R1 fabric is treated with a Hei-Q Pure process to help with odor control, and we found that it resisted odor admirably, even if we sweat into it. There are strategic zones of Capilene Cool fabric around the collar for increased breathability for a part of the body that has higher-than-average sweat rates. The neck has many capillaries and sweat glands, so it’s a spot where you can easily regulate temperature by covering up or uncovering a small area of skin. The collar of this jacket is high and can provide a lot of warmth in colder conditions.

Patagonia is a brand known for nailing small details. For this jacket, they removed the seams on the shoulders for increased comfort and added stretchy hems for improved fit. The two zip hand pockets are perfect for warming hands up or carrying small items like a hat or gloves. In addition to using this jacket for running, we also often reach for it for casual wear.

Weight: 9.7 ounces (275 grams) | Shell material: 93% recycled polyester, 7% spandex

Shop the Women’s Patagonia R1 Daily JacketShop the Men’s Patagonia R1 Daily Jacket

How to Choose a Winter Running Jacket

For many of us, running in the winter means adding extra layers of clothing to keep warm. The best winter running jacket for you depends entirely on the winter climate you’re running in. Are you facing the endless drizzle of the U.S. Pacific Northwest, where you’ll want to have a waterproof jacket like the Outdoor Research Helium Rain Ultralight Jacket on hand, dealing with the frigid temperatures and snow of Alaska or other high latitude locations, or living in a moderate climate where you just need a little extra warmth when compared to other times of year? There are endless factors to consider when choosing a winter running jacket to ensure you get the right one.

Types of Jackets

Most of the best winter running jackets fit into one of four categories: wind-resistant, water-repellent, waterproof, and insulated.

Wind-resistant jackets are lightweight and compressible, and they are great for creating a warm and comfortable microclimate next to your body when outside temperatures drop. These jackets are generally made of ripstop nylon and are reasonably breathable. Some have extra vents to help control your body temperature and prevent excessive sweating. The Black Diamond Distance Wind Shell is an excellent option for a simple jacket for winter running, and you can read more about these types of jackets in our best windbreaker jacket guide.

Many wind-resistant jackets have a durable water-repellent (DWR) coating to keep them from immediately soaking through if you get stuck out in the rain. While water-resistant jackets are no replacement for a fully waterproof rain jacket, they are often adequate for short showers.

Waterproof jackets are designed to keep you completely dry when it starts to rain or snow. They are generally made from one, two, or 2.5 layers of material and have different breathability and waterproofness ratings, depending on the materials used. Our best running rain jackets guide explains more about the technical fabrics used in fully waterproof jackets.

Insulated jackets come in many forms. Insulation can be made from synthetic materials or down feathers from geese or ducks. As an aerobic activity performed at relatively slow speeds, at least when compared to cycling and Nordic skiing, running generally requires fewer layers for warmth than other sports. A fully insulated jacket is probably overkill unless you’re running temperatures well below freezing. That said, several hybrid insulated jackets, including one of our favorite, the Patagonia Nano-Air Light Hybrid Hoody, place insulation in key areas to provide that extra warmth you might need on a chilly day out.

The Decathlon Forclaz MT100 Hooded Synthetic Jacket is a budget jacket perfect for cold-weather winter runs. Photo: iRunFar/Eszter Horanyi

Fit and Mobility

Every jacket fits slightly differently, and it’s important to consider how you will use it before committing to a size or style. At a very minimum, the sleeves of a jacket should be long enough to cover your wrists and not ride up throughout any part of an arm swing. A properly fitting jacket also shouldn’t expose your midsection when you lift your arms to the sky. Be sure that the length of the jacket provides enough coverage over the hips. Some people like jackets that run long to give the hips some extra warmth.

Jackets can range from a slim fit from some European brands to a boxier silhouette. Narrower jackets, like The North Face ThermoBall Eco Hoodie 2.0, are excellent at trapping extra warmth around the body and can be worn under an additional shell. A wider-fitting jacket, like the Outdoor Research Helium Rain Ultralight Jacket, will let you freely change your base layer choices to accommodate changing weather conditions.

This guide offers several jackets in men’s and women’s cuts. While the jackets’ technical specifications generally don’t change, they are made in different shapes to accommodate different body types.

Packability and Weight

Nothing is worse than going out for a run with a jacket, getting too warm, and being unable to take the jacket off because it won’t fit into a pocket or your running pack. While some of the jackets in this guide can only be carried comfortably in a running vest because of their size, including one of our favorite insulated options, the Patagonia Nano-Air Light Hybrid Hoody, many of them are small enough to fit in a pocket or be tied around your waist without feeling bulky or heavy. When choosing a winter running jacket, consider how you will carry it if you no longer need it on a run. There are several options in our best hydration packs for running guide that can make winter running much easier.

Insulation Type and Placement

When it comes to the best insulated jackets for running, it’s generally a good idea to stay away from down. Down is a lightweight insulator made from goose and duck feathers which can trap warm air in the spaces between them. Unfortunately, it’s a poor insulator when wet as the feathers clump together and can’t trap air anymore, and this makes a jacket fairly useless — and quite heavy — if you sweat through it during a run or get caught in a rain shower. Synthetic insulation mimics down feathers and is a much better option as it retains most of its insulating properties when wet.

Many insulated jackets designed for running or other high-aerobic activities like cross-country skiing or cycling have strategically placed insulation to provide extra warmth in key places while maximizing breathability. Many of these jackets, including one of our favorite hybrid insulated jackets, the La Sportiva Koro Jkt, have insulation around the front of the body and leave the underarms, arms, and even the back uninsulated. This allows the body to vent heat effectively while protecting the core from incoming wind. Jackets with an uninsulated back also make wearing a pack more comfortable since there won’t be insulation to soak up any sweat trapped by the pack.

Our team took jackets out on both fastpacks and day runs to find the best for cold-weather conditions. Photo: iRunFar/Eszter Horanyi

Breathability

As with any piece of running clothing, the breathability of a winter running jacket is important, perhaps even more so than other pieces of running apparel. A breathable jacket will allow moisture from sweat to escape the warm microclimate a jacket creates. If it can’t do so effectively, the moisture will build up inside your jacket, soaking your clothing and skin. While generally this is only incredibly uncomfortable, at worst, it can lead to a dangerous situation in the cold if your base layers get wet. You can explore some options for winter layers in our best base layers for running and best base layers for women guides. Wet clothing conducts heat away from the body rapidly and can leave you shivering before you know it. Choosing a winter running jacket with a high level of breathability can help keep you dry and comfortable. Our testing team appreciated the balance between breathability and warmth in the La Sportiva Koro Jkt.

A fabric’s breathability is measured by how much water vapor it allows to pass through. It’s measured as its Moisture Vapor Transmission Rate (MVTR) in grams of vapor per square meter of fabric per 24 hours. A moderate breathability rating starts at around 10,000 g/m2. A higher MVTR means a more breathable fabric. While this is a useful starting point when assessing a jacket’s breathability, many factors determine how well it performs, and field testing is the best way to evaluate its performance.

Wind Resistance, Waterproofness, and Water Resistance

The winter conditions you run in will ultimately determine the best winter running jacket for your situation.

If you’re regularly running in dry but cold weather, a simple windbreaker with extra layers underneath or a light insulated jacket is probably all you need. You may even be happy with an insulating layer like the Patagonia R1 Daily Jacket. If you frequently find yourself in cold and snowy weather, you may get away with the same setup if it’s cold enough that the snow that lands on you doesn’t melt, but given the body heat you’re probably putting off, it will have to be quite cold to find these conditions. If you’re getting snow at warmer temperatures, you’ll want to consider a jacket with at least some water resistance to keep you dry. Our team found that the water resistance of the Black Diamond Distance Wind Shell was better than that of many other windbreakers.

For those who live in climates with chilly and rainy winters, staying warm becomes somewhat of an art form, and the right winter running jacket can go a long way toward comfort. In these conditions, staying dry becomes increasingly important, and a good rain jacket is necessary. If you’re dealing with precipitation coming down as rain instead of snow, you’ll probably be running in temperatures warm enough to cause you to sweat with a jacket on. This is when a jacket’s breathability becomes even more important. When conditions turn cold and wet, the Outdoor Research Helium Rain Ultralight Jacket has been a long-time favorite of iRunFar testers.

Sustainability Considerations

Many companies are increasingly moving toward using recycled materials whenever possible. Several of the jackets tested for this guide use at least some percentage of recycled insulation in their construction, including the Patagonia Nano-Air Light Hybrid Hoody, La Sportiva Koro Jkt, and the Decathlon Forclaz MT100 Hooded Synthetic Jacket.

Many companies are also moving toward using PFC-free DWR coatings for water resistance. Perfluorinated compounds are highly hydrophobic and great for repelling water, but their production results in a variety of highly toxic byproducts. New DWR coatings make the manufacturing process more environmentally friendly.

For many people in many climates, their summer running jackets will provide enough warmth for winter conditions provided that they’ve layered appropriately underneath. A windbreaker can do a great job of trapping heat next to your body and allowing sweat to evaporate. Wearing an extra layer or two underneath a breathable windbreaker, like the Black Diamond Distance Wind Shell, is a perfectly fine winter setup for dry and cold conditions.

If you’re living in climates where it rains consistently, whether as a downpour or constant slow drizzle, using your summer waterproof jacket as a winter running jacket may be adequate. You’ll want to ensure you’re not sweating through your base layers when running in a rain jacket by being mindful of controlling your body temperature throughout a run. Staying comfortable while running in chilly and rainy conditions is one of the hardest situations to get right, and many of our team members turn to the Outdoor Research Helium Rain Ultralight Jacket for wet situations.

Investing in an insulated jacket for winter running could be a good idea for climates where temperatures drop below freezing. While down jackets are great for trailhead and everyday use, they’re prone to getting wet from sweat and not the best for running. A synthetic insulated jacket can provide extra warmth when temperatures plummet below freezing and you still want to run outside. The Montane Fireball Nano Hooded Jacket is designed for running in sub-freezing temperatures.

What’s the best way to layer under a winter running jacket?

There are many schools of thought on the best way to layer for cold winter activities, which are occasionally contradictory. Still, it’s a general rule of thumb that outside of multi-day winter races in the heart of Alaska in the middle of winter, where some runners will choose to use a vapor barrier system to keep their insulating layers dry while allowing their base layers to get wet, most runners are best off trying to layer in a manner that minimizes their sweating while still staying warm. It’s often a fine line to trod.

A single short- or long-sleeve baselayer under a light windbreaker is enough for only moderately chilly runs. As temperatures get colder, you’ll want to consider adding an extra insulating layer, such as the Patagonia R1 Daily Jacket. On even colder days, you might add an insulating jacket over a layer or two. The Montane Fireball Nano Hooded Jacket is an excellent option for a wide range of temperatures and allows for layers. Wearing multiple layers will enable you to add and remove them as temperatures change during a run.

You can learn more about some of the other components for putting together a wintertime running setup in our best cold weather running gear guide.

iRunFar’s Meghan Hicks tests a jacket in the Wind River mountains of Wyoming. Photo: iRunFar/Eszter Horanyi

What type of insulation is best for a winter running jacket?

Generally, the best winter running jackets use synthetic insulation — generally polyester. Unlike down insulation, synthetic insulation will stay warm even if damp or wet, so you have to worry less about getting it sweaty. That said, dry insulation is always warmer than wet insulation, so even with a synthetic jacket like the Patagonia Nano-Air Light Hybrid Hoody or Montane Fireball Nano Hooded Jacket, two of our favorites, you’ll want to do your best to keep from sweating through it during a hard run.

Down jackets can work when carefully managing your body temperature and avoiding sweating. The iRunFar team regularly uses down jackets for fastpacking trips where weight and compressibility are important. They are also great as trailhead jackets, as they are warmer for the weight than synthetic jackets.

Are there warmth ratings for jackets?

The warmth of clothing can be quantified and measured using a unit called the CLO. This measurement is generally used when creating clothing for everyday situations, but it can also be applied to measuring the warmth of different insulating materials. It’s worth knowing that a higher number means a material is warmer, but it’s generally not a measurement tossed around in the running clothing world.

Down jackets come with both a “fill-power” and fill-weight” rating. Fill power measures the quality of the down in a jacket and its ability to loft and keep you warm. High fill-power down has a better warmth-to-weight ratio than lower fill-power down. Fill weight measures the amount of down in a jacket. Higher numbers for both measurements indicate more warmth.

Synthetic insulation, like that in the Patagonia Nano-Air Light Hybrid Hoody and the La Sportiva Koro Jacket, has a similar measure for the amount of insulation that uses the unit of grams per square meter. Again, a higher number means a warmer jacket.

Alli Hartz of iRunFar tests a hybrid jacket on a winter morning run. Photo: iRunFar/Andy Cochrane

Is there a temperature when it’s too cold to run outside?

Cold temperatures can be brutal on the lungs, especially during hard aerobic or anaerobic activity. Sub-freezing temperatures will affect everyone differently, but the general rule of thumb is to not partake in vigorous exercise if it’s below five degrees Fahrenheit (-15 Celcius). Cold temperatures can damage the membranes of your lungs and potentially cause permanent damage. For the frigid days, a treadmill really is a better option. And if you need to get outside, consider going for a gentle walk instead of a run.

You can learn more about things to consider for winter running at When Is It Too Cold to Run Outside?

Call for Comments

• What techniques do you have to stay running outdoors in the winter?
• Do you have a favorite winter running jacket that we don’t have in this guide?
• What features do you value in a winter running jacket?

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