I have spent a lot of time in the cold working out this method for layering, that allows for changing weather conditions, and changing activity levels.  I’ll separate the approach by torso and legs.

Here is a summary of the layers.

Torso

1. Base layer
2. Wind layer
3. Light insulation
4. Shell
5. Belay jacket (heavy insulation)

Legs

1. Base layer
2. Softshell
3. Belay pants

Base layer

The base layer is the start of the layering system.  It should fit snugly without feeling constricting, as the main purpose of the base layer is to keep your skin dry.  All your sweat should be wicked away from your skin to the outer layers where it can evaporate.

A common question is whether to use wool or synthetic base layers.  High quality merino wool base layers are available.  They are comfortable and good for some conditions.  Synthetics, I find, work better on extended trips.  I reviewed the wool versus synthetic debate previously.

Base layers come in a variety of weights, usually “lightweight”, “midweight”, and “heavy weight”. Sometimes, there is even an extra heavy weight.  For the most part, I stick with lightweight and midweight baselayers.  For the same conditions, I generally tolerate a heavier base layer on my legs than on my torso.  For example, I generally will wear a lightweight shirt, while choosing midweight for my legs.

Wind layer

No insulation on the back where a pack provides all the insulation you need. . . great design.

The next layer for the torso is the wind layer. The wind layer should be a very light wind shell, that is extremely breathable.  There really is no need for any waterproofing.  In fact, I don’t reapply (DWR) to my wind shells, as I have found they breathe more easily after a few washes.

The idea behind the wind layer is to allow all that perspiration to pass through, and then evaporate without chilling your core.  For this reason, I personally prefer a vest, as my arms seem to do just fine without a wind layer, so I see no need for the extra weight and reduced mobility of sleeves.

I reviewed the Marmot Driclime vest.

Light insulation

The purpose of the light insulation layer is purely to keep you comfortable (meaning slightly cool) while you are moving.  Carrying a pack, climbing, preparing camp, etc are all hard work and lots of insulation just isn’t necessary.

I have a variety of light fleece sweaters that I use depending on the overall expected conditions.  If temperatures will be above 0F much of the day, I’ll use a 100 weight fleece sweater or pullover if I need it.  Close to 32F, I am usually only wearing my base layer and my wind layer.  Below 0F, a 200 weight fleece sweater, usually fill zip with a hood is a good option.  For consistently severe cold, there are other options that can be lighter than fleece, such as thin synthetic insulated sweaters.  I tend not to use down for such a piece as it will get wet from sweat.  I also avoid the use of wool sweaters unless it is only a day hike.

Shell for the Torso

A shell jacket is still useful in extreme cold weather, however, it needs to be highly breathable.  Being waterproof is less of a necessity the colder the temperatures.  The likelihood of encountering liquid water is very low.  Wind resistance is critically important, as wide open and cold places tend to have very strong winds. Even light shells with DWR shed snowfall well enough.

I avoid the high cost waterproof breathable hard shells because my shell is going to get abused against rock, and there is a lot of risk of damage from ice tools, ice screws, and other sharp implements common in the cold.  And, as I mentioned, waterproofing isn’t a critical quality of a good extreme cold weather shell.

I’ve used the Marmot Precip jacket for years now in various forms.  It is a nice, light, and inexpensive option for a shell.

Belay jacket and pants

Leukotape patch on my DAS

The belay jacket and pants are common for winter climbing and mountaineering.  The idea is to have heavy insulation for periods without much movement.  These should be thick puffy garments full of synthetic insulation, as they go on over the top of all the sweaty layers from the day.

For the legs, full side zips are important so that boots do not need to be removed.  These garments must be sized to fit over the top of all of the other layers.

I discussed the belay jacket concept more thoroughly in the past, including my preference for the Patagonia DAS Parka and Patagonia Micro puff pants

Softshell for the legs

On my legs, I can tolerate one system much more easily because my legs aren’t full of critical organs that need to be closely temperature regulated.  In addition, I’m often wearing a climbing harness which precludes the ability to quickly, easily, and safely add or remove layers as conditions change.  These reasons lead to softshell being a more ideal system for the legs.

Softshell is suitable for a wide variety of conditions, more so than the traditional 3 layer system.  It is a light, breathable, and comfortable system.

I reviewed my favorite softshell pants, the Patagonia Mixmasters in the past.

Conclusion

The 5 layer approach for the torso, of base, wind, light insulation, light shell, and belay jacket, as well as the 3 layer approach for the legs of base, softshell, and belay pants works very well in a wide range of extreme cold weather and severe conditions.  I’ve used and abused this system for quite a while now, and have no reservations relying on it to keep me safe and comfortable in the mountains.

For more information about cold weather clothing choices, Extreme Alpinism: Climbing Light, Fast, and High by Mark Twight is a very good resource.

For more information about sleeping in the cold, see my article about cold weather sleep systems.

I hope this helps.  Let me know!

Prepared for a cold night in the Andes

I take a good look at the historical temperature and weather data.  This helps me to select equipment.  The first piece of equipment most of us think about for our sleep system is the sleeping bag.

Sleeping Bag

One of the rules of thumb I hear often is to use a sleeping bag rated to 10F degrees lower than the coldest temperature you expect to see.  Personally, I find this is pretty bad advice for three reasons.

First, on a longer trip, there are going to be warm days and cold days.  There is nothing worse than sweating all night in a bag because unzipping the bag leaves you too chilled, but the bag is too heavy for the temperatures you are seeing that night.  This is very easy to experience in sub zero temperatures.  A bag rated for –40F is going to feel really warm in -20F conditions, but –20F is really cold if you aren’t wrapped up in that sleeping bag.

Second, there is no reason not to utilize the insulation you are packing for the day.  Those layers of clothes are effective insulation during the day and at night.  In addition, I’m not a fan of stripping down out of my layers in sub-zero temperatures and getting dressed again in the morning.  It just isn’t comfortable and can be pretty dangerous to expose yourself to serious cold.  Sleeping in my clothes is standard.

Finally, there are a few other things you can use to increase your insulation when the temperatures plunge lower.  First, I’ll throw my belay jacket over the top of my sleeping bag.  I’ll wear a balaclava to sleep. A sleeping pad and proper shelter from the wind can help dramatically as well.  A sturdy water bottle filled with hot water can also help warm things up in the bag.  Use this method with caution as a leak could be disastrous.

This is why I usually select a bag that is rated to temperatures 10 to 20F above the temperatures I’m expecting.  I like a –20F bag for anything down to –40F or so.  Similarly, a 20F bag is just fine down to 0F.  By taking a bag rated that way, I get some weight savings, which is always important.

An important point to keep in mind is to never pull your face inside your sleeping bag.  You exhale large quantities of moisture which will penetrate the insulation in your bag and cause cold spots and problems.  Don’t do it.

Sleeping Pad

The ground is generally a far better conductor of heat than the air.  It is vitally important to have good insulation between your body and the ground.  Your sleeping bag isn’t enough, because your body compresses the bag where you lay on it, and prevents it from holding nice warm air in the insulation.

I have used foam pads as my sleeping pads extensively.  I’ll still use foam in very warm weather.  Closed cell foam is a great pad material.  I strongly recommend carrying at least a small square to sit on in the winter.  This could be the back pad/frame of a daypack or summit pack.

There are now much better choices for extreme cold weather.  Various inflatable pads offer much better protection from cold ground.  Just like your fluffy down sleeping bag holds warm air close to you, an inflatable pad holds warm air close to you.  These can be insulated with synthetic materials, foam, or down.

My long time favorite is the Thermarest pad.  I have one that is about 15 years old, and it still works great.  I’ve upgraded to a down filled air mat, in hopes that the greater ground insulation allows me to push my sleep system to even colder temperatures.

Shelter

A good shelter is a necessity to protect from the wind and any snow / ice getting blown around.  I’ll sleep under the stars in hot weather, but in extreme cold, the consequences of not having shelter are substantially more severe.  I’ve used a variety of shelters, from tarps, to snow caves, to tents.  They are all good options and I’ll continue to use all of those options.  However, I do have a preference for tents for a few reasons.

Snow shelters are slow to build.  They take a lot of time, and can be difficult in certain snow conditions.  This takes a lot of time each day if you are moving from camp to camp.  However, they are warm and really weatherproof.  You can get away with a much lighter sleeping bag if you use good snow shelters.  They are a great option for base-camps.

Tarps are fast and light, but don’t protect like a tent or snow shelter.  They can be used to make faster snow shelters, like a trench shelter with the tarp over the top.  I like tarps quite a bit because of this versatility and light weight.  However, in general, a tarp will offer the least protection from brutal wind and wind driven snow that is often seen at altitude.

Tents are more weatherproof than tarps, and faster than snow shelters.  They are the middle ground.  I prefer a very light and simple single wall tent for the bulk of cold weather situations.  I prefer to size the tent as small as possible so that my body heat is able to warm the interior quite a bit.  The key is to have lots of guy line available.  This allows you to anchor the tent securely even in harsh conditions.

A very light tarp is handy to have even with a tent or snow shelter because it allows you to have a protected kitchen / dining area.  Cutting the wind not only keeps you warmer, but can help increase the efficiency of your cooking system.  The weight of the tarp can easily pay for itself with a decreased fuel load.  You can also hang clothes to dry under a tarp, allowing them to get lots of good airflow, but not get hit with falling snow.

Clothing

When I was a child, I heard that in the winter, it was best to sleep naked or in underwear only.  I’m not sure how or why that rumor developed, but it is ridiculous.  I wear clothes to sleep.  In extreme cold, it isn’t very pleasant to wake up in the morning and put on cold, frozen-stiff clothes.  That means I keep my clothes in my sleeping bag at night anyway.  So, rather than wasting that insulation value by padding the foot of my sleeping bag, I keep the clothes on and wear them to sleep.  The key is not to overstuff my sleeping bag though.  This means I don’t wear my belay jacket into the sleeping bag because it is too big and the insulation ends up compressed.  Instead, I drape it over the top of my sleeping bag, over the chest area to add a bit more insulation where it matters.

I have an old habit of putting any wind shell layers between my sleeping bag and sleeping pad.  In the past, before I had a thick, high insulating value sleeping pad and a sleeping bag with a waterproof breathable shell, I’d often find frost between my bag and pad.  I’d put my shell between my sleeping bag and sleeping pad to prevent the possibility of them freezing together during the night.  I haven’t experienced the frost issues anymore, but I still often tuck my wind shells under my sleeping bag to keep them warm.

Finally, the same clothing practices that keep you warm on the move will keep you warm in your sleeping bag.  A nice dry pair of thick socks works wonders for keeping the feet comfortable.  I’ll usually have my wool hat and my balaclava tucked in the hood of my sleeping bag.  If I get cold, particularly as the night goes on and gets colder, I can layer my hats to hold in the heat, and the balaclava prevents the temptation to bury my face in the sleeping bag and ruin the down insulation.

Some things I haven’t tried but have seen others use to good effect are insulated booties.  Several brands make these, and they are basically down or synthetic insulated booties that are worn into the sleeping bag and inside the tent.  I haven’t really felt the need, as I don’t seem to get cold feet.  But it is something to keep in mind.

Miscellaneous

One of the key things I’ve noticed over the years is the difference between being warm and feeling warm.  Using this system, I am warm and safe.  The first few nights in extreme cold, especially if I’ve just come from a very hot climate, can really be rough.  I feel cold.  But I’m just fine, I am warm and safe.  I simply need to acclimate to the cold, the same way I need to acclimate to altitude.  That is a key point to remember.

Wrap-up

So, what does my extreme cold weather sleep kit look like now?

Bibler Eldorado tent (see my review here)

Exped Downmat 9 (see my review here)

Marmot Col EQ –20F sleeping bag (see my review here)

Patagonia DAS Parka

Patagonia Micro Puff pants

Outdoor Research balaclava

Wool hat

Here are the basic elements that I carry.

1. Leukotape I’m not joking when I say this is my favorite tape.  This has replaced my athletic tape and medical tape in my first aid kit and it has replaced duct tape and/or 100mph tape as my repair tape of choice.  This is the best tape on the market I’ve found.
2. Needles I carry a small supply of needles in a matchsafe.  I still carry some matches as part of my normal load out.  Being able to stitch up some of your soft gear is critical.  Rip your pack?  Stitch it, and seal it.
3. Dental Floss I carry dental floss because it is part of my hygiene gear.  Yes, I floss my teeth.  But, floss is also a very sturdy thread, and it is waxed, so it tends to handle water well.  This is what I use to sew together anything that breaks.
4. Seam Grip This is my go to adhesive for everything.  I rub a little into holes on my clothes to keep them from unraveling further.  If I stitch something, I rub some Seam Grip over the stitches to make sure they last.  This is also the glue I use if I need to patch up an air mattress.
5. Gerber Multipliers I use these extensively.  The screwdrivers are handy if you need to adjust or repair crampons or snowshoes.  I also use them to tear down my stove to clean it.  The pliers are handy for pushing needles through heavy material.
6. Air Mattress Patches This is pretty self explanatory.  Most air mattresses come with a few squares of material that you can use to patch it.
7. Stove Repair Kit I use an MSR stove, so I carry a full repair kit for it.  The important things, in my experience, are having spare O-rings (especially where the fuel tube inserts into the pump), plenty of pump cup oil, and the tools to clean a jet.
8. Tent Parts I’ve never actually had a damaged tent.  I carry a spare bit of guyline these days because it is useful for a lot more than my tent.  Other people I’ve met carry pole repair sleeves, zipper repair kits, etc.  I’ve never damaged a zipper or a pole, so I’ve removed those bits from my kit.  I may not be in the environments that tend to damage those things, although I’m often in serious wind.

That is what I carry for field repairs of my gear on extended duration trips.

1. Leukotape As I’ve mentioned, this is my favorite athletic tape.  Should I sprain an ankle, get a cut, or get some hot spots on my feet, I will use Leukotape to patch myself up.
2. Foot powder in a Nalgene squeeze container I keep some foot powder in a very small Nalgene squeeze container.  This is essential for dusting the Leukotape after I apply it, as well as keeping my feet dry on longer runs.
3. Small med kit I carry a very small med kit that I keep in an Aloksak.  It contains: BZK wipes, Benadryl, Immodium, small butterfly bandages, and Motrin.
4. DEET Bug spray is essential.
5. Headlamp I keep a Black Diamond Gizmo Headlamp in my kit.  It is small and light, and has a blinking function in case I need to signal for help.
6. Knife A small sharp knife is useful in case I need to cut tape or anything else.
7. Lighter Just in case.
8. REI Doubleshot waist pack This is what I use to hold everything.  It is a belt pack that holds two water bottles and has a small pouch to contain my trail running kit, cell phone, and a few gels.  It also has an elastic cord to strap down some extra socks if I’m in wet conditions.  I find it nice and stable.

And that is what I carry on my trail runs.