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An old Swedish proverb advises us that there is no bad weather, only bad clothing. Given that those in the land of Abba and Absolut are no strangers to some of the unfriendliest weather conditions our planet is capable of concocting, there’s a pretty good chance that their words of wisdom are well worth listening to.
With regard to hiking, the Swedes’ weather-savvy smarts can serve us in two ways: both as a call to get out there whatever the conditions and, more importantly, as a reminder to pay particular attention when it comes to our clothing choices.
In this article, we’ll turn our attention to the particulars of the mid layer, that all-important bringer-of-warmth in the backcountry getup. We’ll start off with a look at how the midlayer fits into the layering system as a whole and then jump into what midlayer types are most effective and a review of the best ones out there this year.
In the world of outdoor sports, the layering system is now all but universally recognized as the optimal solution for active attire. It works, in essence, by using multiple strata of clothing each designed to work in unison with and complement the others:
This three-part system is held together by one indispensable feature: breathability.
‘Breathability’, in short, refers to a fabric’s capacity to transfer moisture (i.e. sweat) from inside to out, allowing it to pass from the interior layer right through to the exterior of the final layer, where it can evaporate more quickly.
Breathability is vital to layering because any non-breathable layer will block the movement of moisture from one layer to another, thereby causing a buildup which can lead to saturated fabrics and, in extreme cases, hypothermia. As such, if any garment in the layering system lacks breathability, the whole system will collapse.
To offer an analogy, a non-breathable layer in effect acts like the gases which create our planet’s “greenhouse effect” by trapping in what really needs to be out — in the case of hikers, our sweat. Thinner, breathable layers, conversely, offer less of a barrier to the transfer of excess moisture, allowing it to pass through each layer in turn and evaporate in the ambient air.
The instinctive move in colder conditions is to throw on heavier, bulkier garments, but bulk and weight alone aren’t necessarily enough to keep us warm for two main reasons:
1. Bulkier layers are often too thick to breathe well, meaning moisture becomes trapped inside the layer. Because water can conduct heat away from the body 25 times faster than air, if this moisture is then allowed to cool excessively — if, for example, there is a drop in temperature or we stop moving — then our core temperature can drop rapidly, leaving us vulnerable to hypothermia.
2. Even when not working up a sweat, a thicker layer might not insulate as well as two much thinner layers. When we use thinner layers, small air pockets are created between each item of clothing. These pockets are where our body heat is trapped, thus creating an additional, weightless, invisible, and — maybe most importantly! — free layer that acts as an added buffer and insulator.
So, just how does the midlayer function in the layering system as a whole?
While the baselayer and outer or “shell” layer take care of moisture management and protection from the elements respectively, the midlayer is all about heat retention and insulation — so much so, in fact, that it is often referred to simply as the “insulating layer”.
The midlayer works by trapping body heat close to your body. One common misconception is that insulating clothing items provide heat in and of themselves, whereas the truth is that, while they may forestall heat loss by keeping the elements at bay, the heat we feel when wearing these items derives from their ability to limit the loss of the heat generated by our bodies.
One way to see this for yourself is to simply pluck a meaty midlayer from your shelves and feel how warm it is. Not very, right? And this is exactly the point — a midlayer works by retention, not the active production of heat.
The short answer to the above question reads as follows: any time that temps are not so high that you are able to wear just a t-shirt or vest.
At other times, a midlayer will either be worn as an outer layer in itself or between the baselayer and the shell layer.
When an outer shell is not required to fend off precipitation or wind but it’s too chilly to wear a t-shirt alone, then your midlayer becomes the barrier between you and the elements and ambient air. In these circumstances, a midlayer with some degree of wind and water resistance is preferable. As such, standard fleece and wool midlayers are not your best bet as these usually offer little wind-resistance and — although both can insulate when wet — are prone to soaking up liquid very quickly.
In colder temps, your midlayer is crucial in maintaining body heat — your baselayer and shell layer alone will only do so much and in temps south of 55F are unlikely to prove adequate for most. In this scenario, wind and water resistance is not such a big deal as the outer shell will provide both. Instead, breathability comes to the fore — without it, your midlayer will trap sweat inside and leave you exposed the dangers mentioned above (a bad dose of the chills and possibly hypothermia).
When buying a midlayer the key components to consider are insulation, breathability, and comfort, all of which rely to a large extent on the midlayer’s fabric type.
A midlayer that doesn’t insulate is not entirely useless — some varieties, for instance, offer almost zero insulation but have other important attributes such as wind or water resistance. When hiking in cooler conditions, however, insulation is critical to staying warm as baselayers and shell layers alone offer very little in terms of heat retention.
Whether you’re buying down, wool, or fleece, each product will denote the degree of insulation it provides with one of the following:
How much insulation you require will depend, ultimately, on the conditions in which you do most of your hiking.
For warm-weather hikers, a lighter, thinner midlayer (in the 300-500 fill power range for down and 80-150 gsm range for wool or fleece) will be adequate to deal with the odd breeze or cooler morning and evening temps. For winter wanderers or those hiking at altitude, however, investing in a more substantial midlayer (circa 800 fill power for down, 200+ gsm for fleece or wool) is a wiser choice.
As mentioned above, breathability is a key and must-have facet in any midlayer. Whether worn between your baselayer and shell or on its own, a midlayer that lacks breathability will prevent sweat from escaping and leave you a prime candidate for rapid heat loss and even hypothermia.
Generally speaking, down, fleece, and merino wool products all breathe very well, with some variation between thicker models and lightweight options which results in a trade-off between breathability and warmth.
One fabric that is a particularly poor performer in terms of breathability is cotton, which should be avoided at all costs.
In midlayers, a number of factors and features contribute to comfort, with the most important being fabric type. Below, we’ll take a look at the most common types of midlayer fabric and provide the lowdown on their benefits and drawbacks.
Down performs best in dry and cold conditions and also offers a great warmth-to-weight ratio. On the downside, most down midlayers range from slightly to exorbitantly pricey and offers little to no insulation when wet.
This relative newcomer to the hiking world has rectified down’s greatest failing by making it a solid insulator even in wet conditions. At the same time, however, it has taken down’s other great drawback — the price — to a whole new level of horrible.
A nice option for those prepared to part with a sizable chunk of their savings in return for top performance.
In recent years brands such as Icebreaker and Smartwool have reinvented the heavy, itchy, unsightly affairs once knitted by our grandmothers and made them into something of a staple for the performance-minded outdoorsperson.
Wool midlayers — and merino varieties in particular — offer similar wicking capabilities to fleece and other synthetic fabrics, but insulate slightly better when wet and usually smell fresher after a long day on the trail. On the downside, unless used in a blend with other synthetic materials, wool offers very little wind resistance when worn as an outer layer and, particularly in more substantial models, can cost a small fortune.
This lightweight, quick-drying fabric is a long-term favorite of outdoors enthusiasts everywhere. And with good reason…
It isn’t quite as compressible as other mid layer fabrics and offers very little in the way of wind resistance, but otherwise is a high-performing option that is soft, cozy, can insulate even when wet, and usually costs a lot less than merino or down. Some examples of big-name fleece products you might find are Polartec (Rab, Patagonia, Black Diamond), Pontetorto Tecnopile (Mountain Equipment), and Gore Windstopper. Read here the about the best fleece jackets for the outdoors!
Many other synthetic midlayers now provide additional, high-performing alternatives to the hiking staples mentioned above, most notably polyester-based products and fleece variants such as Polartec (various brands) and Omni-Shield (Columbia), which offer both excellent insulation and breathability. Where these midlayers really excel, in most cases, is that their tight-knit fabrics boast superior wind and water resistance to most standard fleece and wool products.
The features in a midlayer most worth having are those which offer the most versatility with regard to temperature regulation. To put it simply, each of the following allows you to increase or decrease the level of insulation in your layering system without shedding or adding a layer, simply by making fine adjustments to the insulating layer itself.
This seemingly negligible feature is an excellent addition to any midlayer, allowing you to prevent cool air entering and warm air escaping at the wrist in cooler conditions or vice-versa when things start heating up.
A full-length or quarter-length zipper might not seem like a major selling point in any item of clothing, but a zipper is undoubtedly the quickest and most effective way of cooling down when need be — short of, that is, shedding the layer entirely. When approaching an uphill section on your hike or the sun pokes its head out from behind a bank of clouds, simply pull down the zippers to let in a little air and then zip up again when needed.
Whether wearing your midlayer under a shell layer or on the outside, a hood is a handy addition for three reasons:
While not an obvious dealbreaker or maker, pockets are a handy feature in any hiking garment. Should you have to shed your shell layer when out on the trails, having a pocket or two in which you can carry a map, GPS device, or camera will save you the hassle of having to doff your pack every five minutes to take readings or snap your shots.
In terms of temperature regulation, pockets can be opened to allow air flow into the baselayer when temps perk up, and when things cool down you can, of course, stick your hands in them.
A “drop back hem” refers the extra material added in some midlayer models to cover the top of your posterior or, at a minimum, prevent cold air sneaking in between your pants and the base of your top.
While not as adjustable as zippers or a hood, if the hem of your midlayer has an elasticized drawstring then the it can be opened and closed to adjust airflow as and when required.
Now that we’ve covered all the things to look for in a good midlayer, let’s move onto the business end of things with our selection of the best midlayers in 2018.
With the Rab Superflux Hoody we get our review underway with a wonderfully versatile midlayer that ticks every box in our list of desirable features and sets the bar scarily high for its competitors.
Made with high-performing thermic fleece, this hoody offers more in the way of weather resistance than standard fleece products owing to a closer knit and brushed-back finish. At the same time, it retains a high level of breathability and works well either as a stand-alone outer or the insulating filler in the full, three-part layering sandwich.
The Superflux is boasts a full complement of handy features, too, including thumb loops, a large chest pocket, and close-fitting hood that won’t rattle in the wind.
In short, a high-performing all-rounder that will endear everyone not overly put off by the lack of hand pockets.
Using Pintetorto Tecnopile fleece, the Montane Fury is possibly the softest, coziest hoodie you’re ever likely to come across. And it’s none too shabby in other respects, too. Boasting stretch panels on the sides and underarms for unrestricted movement, three exterior pockets, an adjustable hem and hood, this is a top that marries the performance demanded by the athlete with the warmth and comfort demanded by those looking for a soft, snug safeguard for cool nights in the campsite.
The downsides to the Fury are ones of degree rather than out-and-out failings or absences. It’s a little less wind resistant than other items in our review and won’t deal very well with a rain shower, but otherwise, it’s an affordable, functional option.
From its super-soft Polartec High Loft Fleece fabric to its full feature set, there’s a lot to love about Mountain Hardwear’s incredibly popular Monkey Man II. This is the kind of fleece that’s so warm and comfortable that you won’t want to take it off, and if you pay a visit to any mountainous hiking hub around the world — Chamonix, Yosemite, Cortina D’Ampezzo — you’ll be sure to see plenty of snug-looking Monkey Man users to prove it!
One of the warmest items in our review, the Monkey Man II doesn’t let its ability to trap body heat hold it back performance-wise. It’s high-wicking, breathable, quick-drying, and has a tight enough knit to deal with buffeting winds. It isn’t water resistant and not the lightest item in our review, but for a few extra ounces you get a lot of extra warmth.
If you can manage (and have the bank balance) to see past the eye-watering price, the Icebreaker Descenderwill soon give you plenty of reasons to believe you’ve actually got yourself something of a bargain.
This superbly comfortable top uses 240 weight merino for optimal 3/4-season warmth in combination with stretchy synthetics that allow for unrestricted movement and a very athletic fit. It’s cut long in the rear and sleeves to avoid drafts squeezing in when you’re on the move, and features-wise packs everything you could ask for with the exception of a hood.
A superbly practical midlayer that weighs in at just 9.8 oz and packs over 150 gsm of very comfortable Polartec Classic fleece, the Delta LT is made for those who like to move fast and light.
It also boasts a full set of features and throws in a few bonus ones to boot — a laminated zipper so it can be easily located in the dark and a comfy chin guard that prevents drafts entering around the neck. Frills aside, where the Delta really excels is its wind and water resistance, offering enough of both that it performs just as well as a stand-alone outer as it does when worn in conjunction with a shell.
All in all, a wonderfully functional fleece that will serve you well anytime, anywhere.
Using a higher density fabric (180 gsm2) than the Arcteryx Delta LT, the Black Diamond Coefficient is a warmer midlayer ideal for those who do their hiking at altitude or in winter months. Made with Polartec’s excellently breathable Power Dry fabric, the Coefficient’s warmth doesn’t detract from its performance and it’s as much at home on high mountain trails as it is at the campsite.
It may be pricey compared to some items in our review, but those who choose the Coefficient are effectively getting two garments in one — a toasty insulator in a three-part layering system and a solid, reliable outer when worn alone.
In short, a great choice for the cold-weather hiker.
The most expensive item on our list, the Cerium LT’s price tag will likely scare off many a would-be buyer before they even get down to reading about the many benefits this high-performing, luxurious midlayer has to offer.
As a stand-alone midlayer, the Cerium LT is, granted, frighteningly priced. However, it justifies that price by offering a very versatile option that really ups the ante in terms of insulation and performance.
The Cerium uses 850 fill goose down that is body mapped to boost heat in targeted areas. In addition to this, it uses a backup, synthetic CoreLoft fill that ensures it will keep you warm even when wet and also an effective DWR (Durable Water Repellent) finish that puts the proverbial cherry on top of the cake by helping to avoid getting it wet in the first place.
The bottom line? It’s water resistant, light, comfortable, cozy as can be, and a great cold-weather companion for those who don’t mind paying a high premium for the privilege.
|Model||Fabric||Level of Insulation||Features||Value for Money|
|Rab Superflux Hoody |
|94% polyester, 6% spandex||Medium||Large chest pocket; thumb loops; hood; full-length zipper||Very good: a top performer as either a wear-alone outer or an in-between insulator|
|Montane Fury Hoodie |
|94% polyester, 6% spandex||Medium||Large chest pocket; zippered hand pockets; thumb loops; hood; full-length zipper||Very good: the cheapest option in our review and a solid performer despite its lack of weather resistance|
|Mountain Hardwear Monkey Man Grid II |
|Synthetic Polartec High Loft Grid||Medium/High||Hand pockets; thumb loops; hood (optional); full-length zipper||Good: Not ideal as stand-alone outer due to lack of water resistance but offers excellent warmth and comfort|
|Icebreaker Descender Long Sleeve Zip |
|Merino-polyester blend (84% merino)||Medium||Large chest pocket; zippered hand pockets; thumb loops; hood; full-length zipper||Very good: it’s pricey, but it packs a lot of warmth and performance|
|Arcteryx Delta LT Jacket||Polartec Classic||Medium||Sleeve pocket; zippered hand pockets; thumb loops; full-length zipper; chin guard; laminated zipper||Good: excellent performance but loses points for lack of hood|
|Black Diamond Coefficient Fleece Hoody||Polartec Power Dry||Medium/High||Large chest pocket; zippered hand pockets; thumb loops; hood; full-length zipper||Very good: not cheap but a wear-anywhere, anytime kind of midlayer|
|Arc’teryx Cerium LT Hoody |
|850 fill European Goose down; Coreloft 80 (80 g/m²) insulation; 10 denier nylon shell||High||Interior pocket; zippered hand pockets; hood; full-length zipper||Good: Very expensive but well enough made and durable enough to be a once-in-a-lifetime purchase|
The modern hiker is somewhat spoiled for choice with regard to high-performing midlayer options. In our review we’ve seen a little bit of everything, and narrowing down the best of our cream-of-the-crop selection to an out-and-out winner hasn’t been easy.
When push came to shove, however, we based our evaluation of each midlayer’s merits on three must-have attributes — a solid warmth-to-weight ratio, overall performance, and value for money — and in each of these categories found the Arcteryx Delta LT Jacket to come up trumps over the competition.
This feature-rich, fantastically practical top offers the kind of versatility that makes it suitable for use any environment, whether as a stand-alone outer or an interior insulator. It’s also incredibly light, packable, breathable, and does more than enough in terms of heat retention and warmth to justify its slightly hefty price tag.
Sam Hardy is an outdoor enthusiast with a penchant for survival skills. He writes about the great outdoors and his favorite equipment here.