It may seem counterintuitive to think about how to keep cool while skiing--especially when the weather report calls for low temperatures--but making smart decisions about what layers to wear while touring (and when to add or remove them) can be one of the most important decisions you'll make in the backcountry.

Comfort is important, but performance and safety are also impacted by your layering system.

Exum guide Brenton Reagan starting climbing in the Tetons when he was 14 and has been working as a guide in the area since 2001. He's an expert on many things, including how to safely and efficiently layer for ski touring. (We met while he was guiding a steep skiing clinic I took.)

As a note, Exum guides are partnered with Arc'teryx, so most of Reagan's kit comes from the brand. However, this can also be used as a guide for pieces from other brands.

Go feet first.
Look for a knee-high wool sock that will keep your feet dry and provide added warmth to your calves. Stay away from cotton, no matter what. Reagan likes Farm to Feet. Here are some others we have tested.

Start with a strong foundation.
Touring is an aerobic activity--your body is going to get warm--but if it gets too hot, you're going to sweat. That sweat will eventually cool, leaving you cold and wet, which is not only miserable but also dangerous in the backcountry. To avoid all of the above, a moisture-wicking base layer can make a big difference by keeping you cool on the uphill and warm in the transitions.

Read more: How to Wash Your Ski Gear.

Reagan recommends the Arc'teryx Phasic Sun Hooded Shirt for lightweight protection year round. (Garments worn by fly fishers inspired the design.) The Phasic polyester material is moisture wicking and has a UPF 50+ sun protection rating. He also suggests sizing up for a looser fit.

Phasic Sun Hooded Shirt. PHOTO: Arc’teryx

"In winter I can pull up the hood over my baseball hat and stay warm if it's snowing a ton, which helps keeps the head regulated," he says. "In the summer, it's not so much about staying cool but keeping the sun off. All the guides have started wearing them in summer and winter for touring."

Phasic Sun Hooded Shirt for men: Buy now.
Phasic Sun Hooded Shirt for women: Buy now.

If it’s midwinter, you'll likely be touring in a shell pant. For the bottom base layer, Reagan suggests looking for a wool material that also has some stretch. He opts for the Rho LT, a lightweight pant that's soft against the skin and doesn't limit mobility.

Rho LT Bottom. PHOTO: Arc’teryx

(I've skied in the women's version and can vouch for their incredible fit, comfort, and function. I often get cold legs when I wear shell pants, but when combined with this as my bottom base layer, my temperature is perfect for the up and the down, especially when the wind starts whipping.)

Rho LT Bottom for men: Buy now.
Rho LT Bottom for women: Buy now.

Get a leg up.
Whether you prefer bibs or traditional pants, opt for a waterproof, breathable shell with venting capabilities that will allow you to seal out weather or quickly dump heat. Since you won't be able to add or remove layers on your legs while touring, venting is the best way to customize your temperature.

Reagan suggests leaving the vents wide open on the way up if you run hot and zipping up during your transitions. If you're worried about not being warm enough, keep in mind you'll have a much easier time adding layers to your upper body where you organs live.

A couple pieces that have received high marks by POWDER readers last season include the Arc'teryx Stinger Bib for men and the Shashka Pant for women. The best pants of the year from the current season can be found here for women and here for men.

Shashka Pant for women. PHOTO: Arc’teryx

Stinger Bib for men: Buy now.
Shaska Pant (that’s actually a bib) for women: Buy now.

Stay warm by keeping cool.
Your upper body is where you have the flexibility to easily add or remove layers to regulate the temperature of your whole body. Ultimately, you want to avoid overheating to the point of sweating, while not allowing your muscles to tense up for being too cold. Yes, it takes practice.

The layers you start with depend on your day's objective, says Reagan. (He throws on an extra jacket while getting ready in the parking lot when it's cold and windy. Then he can ditch it before heading out.)

"If I'm guiding and we're going ski touring and the objective is powder-skiing based, I'm usually going to recommend that people start warm because it's more fun," says Reagan. "But if we're going to ski a Teton peak or a super heavy objective, I say be bold and start cold because I know I will be warm fast."

Procline Hybrid Hooded Jacket. PHOTO: Arc’teryx

Over the Procline Sun Hooded Shirt, which is worn next to skin, Reagan starts with the Procline Hybrid Hooded Jacket made from air-permeable, stretchy Polartec fleece. It has a DWR treatment to shed moisture if you're wearing it as your outer-most shell in light snow and blocks wind while still providing adequate breathability. The hood snugs up nicely if you need to seal out the wind. (For lighter-weight option, try the Proton LT Hoody.)

Procline Hybrid Hooded Jacket for men: Buy now.
Procline Hybrid Hooded Jacket for women: Buy now.

Whatever your second layer is (after your base layer), make sure it's slim enough to be worn underneath a puffy, which you should zip into during any breaks longer than 10 minutes or for transitions. By adding the puffy over the hoody, you're able to store all of the heat trapped against your body.

Reagan's go-to is the Nuclei AR Jacket. The fully seam-taped GORE Thermium shell is windproof and water-resistant. It runs a bit large because it's made to layer. Unfortunately, it doesn't come in a women's version but my experience with the comparable Atom SL Hoody has been more than satisfactory.

Nuclei AR Jacket. PHOTO: Arc’teryx

VIDEO: Watch 100 Years of Ski Fashion Evolve in 5 Minutes.

So when is time to bite the bullet and strip down a layer to avoid overheating? "As soon as I start to feel that my hands and feet are warm, I just skin in the Procline Hybrid Hoody and Procline Sun Hoody," says Reagan. "That combination keeps me warm in my chest and shoulders, though I can feel the wind come through some."

Nuclei AR Jacket for men: Buy now.
Atom SL Hoody for women: Buy now.

At your final transition before the ski down, or to block the wind and any real moisture like heavy snow, a Gore-Tex shell like Alpha AR Jacket will do the trick. Keep it stored in your pack for easy access, then zip it on over the layers to trap heat.

Alpha AR Jacket for women. PHOTO: Arc’teryx

Alpha AR Jacket for men: Buy now.
Alpha AR Jacket for women: Buy now.

Cap it off.
Unless you're in a mountaineering situation that requires a helmet, Reagan recommends a ball cap for the tour to keep the sun off your skin and out of your eyes. Unlike a beanie, a brimmed hat will also keep your head from sweating, which can lead to wet hair that is more likely to freeze than dry. Wet hair is heavy and cold; try to avoid it. During breaks or transitions, pull up a hood or two (or three) to prevent body heat from escaping through your noggin.

More pro tips:
1. Whether guiding or out for a casual tour, Reagan always carries an extra pair of gloves or mittens in his pack. He likes the Rush SV Glove, for touring up and skiing down, because he's still able to tie knots or handle carabiners while keeping his hands warm.

Rush SV Glove. PHOTO: Arc’teryx

"It might seem like kind of a heavy glove, but they've been working well for me. I can put them on my ski poles if I get too warm," he says. "They're comfortable and big which makes them easy to get on and off. It's nice when some things are easy."

2. Reagan doesn't bother with extra hats because so many of the layers he wears have hoods that can be layered in an emergency.

3. Adding or stripping layers should never interfere with safety. Your beacon should be worn over your bibs and somewhere where you're not going to move it.