Knowing the importance of each layer, and how to wear them, plays a huge role in staying warm (and dry) in chilly temps. Layering is as practical as it gets, particularly when it comes to winter running. In cold weather, your dual and complementary objectives are temperature regulation and moisture management: keeping warm without overheating and staying dry from both outside precipitation and personal perspiration. Unfortunately, those goals can be at direct odds. Fortunately, by mastering the art of layering you can still get them right.

Base Layer

The base is the first or next-to-skin layer that exists to wick moisture away from the body, moving it to the mid-layer or vented areas in vapor or liquid form. Base layers should dry quickly, ward off stench, be soft, non-abrasive, and help with thermoregulation. That’s why wool—at least in the non-itchy, soft Merino form—makes such a fine base, and it’s why cotton, which retains moisture, makes a terrible one. Because most base layers work via the mechanics of their fibers—whether natural or synthetic—it’s best when they are snug against the skin. This is why Nordic skiers are often seen wearing Craft or Helly Hansen and why Under Armour took off so well: Form-fitting is the secret sauce to a base layer’s functionality.

Mid-Layer

The second layer is a thermal or performance layer that serves to manage moisture and—depending on outside temperatures and your ability to produce heat—insulate. The mid-layer works in tandem with the base layer to transfer moisture away from the skin, and so performance fabrics are often made of hydrophobic materials with spacious weaves, puffiness, fleece, quilting, down, or fiber-filled materials—all with high warmth-to-weight ratios. Vests make excellent mid-layers.

Outer Layer

Waterproof and breathable. These two characteristics are the most desirable qualities of an outer shell and they are also the most difficult to achieve—at least in the same garment. Technical fabrics have made great progress towards these competing goals. Yet, success depends on humidity, exertion levels, and inner and outer temperatures. Outerwear features include element proofing, seam sealing, hoods, pit or core zips, vents, packability, pliability (and noise reduction), and reflectivity.

Face-Off: Two High-End Winter Jackets

If you’re shivering through the snowy miles this winter, then zip up a high-tech jacket as your top layer to stay warm. With lots of new tech and insulation on the market, you’ve got no excuse to stay inside—no matter the weather. These two options should help triathletes easily ward off winter chills.

Arc’Teryx Norvan SL Insulated Hoody

$500 | arcteryx.com

What

An insulated, lightweight, hooded, waterproof, and pack- able jacket that will get you through the gnarliest of frigid, wet, and windy winter conditions. Made with the lightest of technical materials, the Norvan SL combines lofty insulation and breathable waterproof qualities.

Pros

Bomber protection with a built-in thermal layer of Coreloft Compact 40, down-like polyester insulating fibers and a moisture-wicking liner that allows excess heat to escape. The jacket has a trim cut and a bulk-defying design that engenders cozy, parka-like characteristics. The hood can be snapped down when temps warm. Other bonus features include seam sealing, a waterproof front zip with a chin guard, and cuff reflectivity for this otherwise stealthy, almost leather-esque, matte black piece.

Cons

Cost, of course, and in certain climates the jacket may be overkill. The lack of venting options make it kind of a sealed eco- system, one that could quickly become a moist oven—the price you pay for insulation and waterproofness.

This is for

Inclement, bone-chilling runs when you need a dependable, insulated shield.

Goldwin Light Warmer Jacket

$330 | golwin-sports.com

What

Insulation as either a midlayer or outer jacket that will accelerate your warm-up and moderate your core temperature without cooking you because of its airy, thermo-regulating qual- ities. The breathability and lack of weight of this hoodless, soft, and comfortable piece make it well-suited for a variety of athletic endeavors, regardless of output levels.

Pros

The Pertex Quantum Air fabric, made of 100% nylon, is durable and manages to be both wind-resistant and breathable— preventing overheating while maintaining a comfortable degree of warmth. The Octo Brushed tricot mesh lining is 100% polyes- ter and helps to retain heat when you need it but without any bulkiness. The lack of hood makes the jacket more amenable to layering or using as an outer shell.

Cons

The relaxed fit put the Light Warmer in the midlayer cate- gory because the cut just isn’t all that sporty for sleek triathletes, making it feel a little on the frumpy side. The lack of hood and water- or snow-resistant qualities also limits the number of days you’d want to wear it on a run without covering it with a more burly shell to protect against precipitation.

This is for

Runners in cold climates who need a breathable layer of insulation—one that can be used as a technical jacket because it is dry outside, or in combination with a waterproof outer shell.

Winner

The Norvan SL Insulated Hoody is truly innovative in its ability to meld superlight water- and wind-proofness with insulation while avoiding bulk.