Friday, December 29, 2023

"Sleeping Rough" in cold climates

Don't take this as the final word on the subject. My hope is that my readers who have more experience on the subject will chime in.

My gut-feel is that I have 400 hard-core readers. I also estimate that 10% will have at least as much experience as I have "sleeping rough" in cold weather and 5% or twenty of you will have a LOT more experience.

Tip #1: Contrary to what your physics teacher told you, Heat goes down

Dead-air spaces insulates. Weight crushes the dead-air spaces out of insulation. Climb into a standard sleeping bag on a snowy surface and 80% of your body-heat will leave your body DOWNWARD. More insulation on top of you will not save your bacon if you are losing 4/5ths of your heat downward.

The standard inner-spring mattress is a miracle but it doesn't always translate well to "rough sleeping'. 

A cot with skirting around the perimeter and ANYTHING dry to create a dead-air space (like garbage bags filled with crumpled newspaper) beneath it WILL save your bacon. Heck, you could throw empty, aluminum beverage cans beneath the cot and it would serve the purpose.

In even more austere situations, piling up dry leaves or straw or corrugated cardboard is an option.

Tip #2: Wet kills

Wetness, regardless of the source, destroys insulation's ability to retain heat. Whether it is from rain or snow-melt or condensate from breathing or sweat. Dampness is your enemy. Even with exotic, synthetic fibers.

Tip # 3: Wind kills

If there is no wind, then the layer of air closest to your skin warms and it will (slowly) move away due to very slight differences in air density. Wind-speed brooms away that warm layer and your heat losses go crazy.

Tip #4: Infrared losses are real

Cloudy nights are much warmer than clear nights. Often to a tune of 20F-to-30F. If you have already addressed insulating yourself from the ground, and have strategies to stay dry and are exploiting terrain, vegetation and structures to kill the wind...then suspending a reflective layer like a space blanket or a poncho with a layer of aluminum foil glued to the lower surface 18 inches above your body (or if resources are limited, above your face) can make a big difference.

Little "cheats"

Body warmers can be your friend. Maybe not every night but certainly on the coldest ones.

If you have access to 110V, then an electric blanket or a "massage mat warmer" is heavenly. They use about 60 Watts but a huge percentage of it warms you instead of your bedroom's walls.

If you have a spouse, they are good for about 100 Watts but much of it will escape in other directions.

If you don't have a spouse, dogs are the next-best alternative. "Three Dog Night" refers to a way to stay warm on the coldest of nights.

If you do not have a spouse (or if she objects to your custom of eating pickled eggs and herring before turning in for the night) and if your dogs ran away, then eating a modest meal that is high in fat shortly before turning in for the night might be an option. You DON'T want to eat so much that you need to make a trip to the outhouse, however.

If resources are limited, then if you can only add "extra insulation" to one thing, insulate your head, face and neck.

If you have enough resources to insulate two areas, head-face-neck and trunk.

The big fake-out is that we feel cold in our extremities first. That is because our bodies are smart and they shut-off blood flow to the extremities first. Fingers, toes, hands and feet can drop down to 34 degrees (and be painful) but have little overall impact on our chances of survival. The same cannot be said for our heads or our core-body temperature. The "head-fake" is that people address hands-and-feet when they should be addressing the more important parts.

Using day-clothes as insulation for sleeping

Opinions differ. My inclination is to use them ON TOP of the stack of blankets/sleeping bags to keep them drier UNLESS the temperatures are dire.


Pick a "camping place" that will protect you from moisture (whether from precipitation, snow-melt, driven by wind or from condensation.

Pick a "camping place" that gets you out of the wind.

Have a plan to get up, off the ground and to insulate beneath you. Prosecute that plan aggressively.

Place a canopy or second, inner tent above your body to reflect infrared losses back to your body. If resources are tight, concentrate on protecting your head which is typically the most exposed (and highest priority) part of your body.

Have several rescue or go-to-hell plans in case the temperature drops to -35 F. Candy bars, hand/body warmers, hot water bottles etc.

Having a plan to avoid having to go outside to visit the latrine is pure gold. A "piss bottle" if you are a guy, for instance or a toilet-seat-on-a-bucket if you are of the fairer sex.


My hope is that my readers whose experience dwarfs my own will pipe up and say "Blah, blah, blah is BS. This is what you SHOULD do" or "Don't try to supress shivering. If your body tells you it wants to shiver, don't argue with it..."  or "Be extra careful to not get sweaty before turning in. Sweat is moisture..."

This is a GREAT time to share stories of those times when you were the coldest or had to survive the coldest night of your life.


  1. Growing up in the 60s and standing all day on a deer stand, if you moved the deer moved to another hunter. Cold but fun. The coldest night i remember was in vietnam, guarding a bridge into hill 65, soaked to the skin as a typhoon was on the way. Woody

  2. Battery powered heated clothing is a thing, there is the name brand stuff as well as less expensive no-name versions. Most of these are fed power via a USB connection. If you have a couple battery banks that you use to power your phone, or some of the Milwaukee or Dewalt battery to USB adapters, then you have some electric heat.

    How you recharge that battery is a different issue, solar is crap in the winter but does some. There are some things that will generate power when over a fire, and there are some that will generate power with physical motion. Best option is to plug it in someplace if that is ever an option.

    The large capacity power banks and high wattage chargers can get you a 25,000 mA battery that charges fully in 3 hours and will power a vest or shirt at low for over a full day.

  3. Years ago some buddies and I often did snowshoe backpack trips into the UP woods and camped out. The best two things you can do are change your underwear and socks and put on a fresh, hooded, insulated sweatshirt before you crawl into the sleeping bag. I got up one morning and it was -18 and I had slept well. And sleep in a small tent and use your snowshoe to shovel some snow up on it. ---ken

  4. Amen to all your observations. A mistake many make is sleeping in the bed of a truck with that huge heat sink immediately below you. Always warmer on the ground.

    WRT IR losses - an old heat transfer trick question is about a shallow dog dish left out on a still, clear, dry desert night when the air temp goes to around 40 F - yep, the dog dish freezes solid because of losses to the 4 Kelvin sky. Common to see in the desert when conditions exist.

    Our answer was to crawl under the skirt of a big fir or other evergreen that reaches to the ground. Sleep on the needles as a vapor barrier. Snow and branches stop wind, additional moisture stays up, and IR is well shielded. Comfy as a bug in a rug in AZ at > 10k ft and below zero F. Just watch out for any other critters already occupying the space :-).

  5. Wool Blanket X 2 was my add to my military sleeping bag. Kept me comfortable even on the Korean DMZ in January.

    One folded lengthwise tripled under me to keep me warm, one on top of me for temperature control.

    Not sure if I'd try the pile of aluminum beverage cans under my cot. Aluminum is an awesome CONDUCTOR of heat/cold.

    A debris hut of pine branches and dry leaves DOES work.

    Some say contractor plastic bags are good, but my experience is I soon am drowning in sweat and soon freezing sweat.

    NOW if you cut the bottoms off both and made a double wall tube tent (Mind the wind direction, best if one end is against a pine tree) and filled the in-between with pine limbs and dry leaves.

    A debris hut, minus the discomfort of a face full of leaves.

    BE Very Careful with a fire in cold weather. Awaking to your sleeping set up smoldering (or worse) make a survival situation much harder. I've SEEN folks in survival training making camp in deep pine duff and trying to have a fire in front of their shelter.

    Happily, the instructors having seen that before but a stop to that idea.

  6. ERJ, for what it is worth last May we camped on snow for a night. Everything you have said (insulation, wet, wind, and infrared) is absolutely true. I slept in a hiking tent with slats to allow moisture to leave, on a pad/air mattress and in long johns and was no colder than other situations I have slept in where I was less well prepared.

    One of the potential issues with putting clothes on the sleeping bag or even a sleeping quilt is that you may sweat, which creates moisture and wet, etc.

    I sleep in long johns when hiking but likely do not need to; I just have memories from one night when I was not well prepared and froze all night.

    A good purchase is the lowest rated temperature sleeping bag that one can afford. The one I own is down to 16 F; that does not include things like a pad and long johns.

    I currently borrow a tent and pad from my brother-in-law but need to get both; the ones I want tend to be more expensive as I want the lowest weight items I can afford.

  7. A thick bed of spruce or pine needles is hard to beat for a field mattress, and in anything less than 6' of snow you can usually get to the center section of a large conifer to get to that bed. Nobody has talked about how BAD cotton is in winter- clothes need to be wool (preferred) or synthetic fleece. Likewise, socks MUST be wool or synthetic, no cotton or blends. Socks should be changed regularly when hiking or doing heavy work to keep feet dry. Hydrate! Easy to get dehydrated, and that affects your body's ability to process food into heat.

  8. I've done plenty of winter camping (when younger - with age comes wisdom, eh?). I agree with all of your points, and would like to emphasize a couple:
    - wilderness first aid teaches that one of the most important things to do for a hurt person who can't move, is to get something, anything, insulating under them. Shock and hypothermia can set in from heat loss to the ground, even if the person isn't wet on the bottom side.
    - I remember reading a non-fiction book about the Soviet Army, and how a soldier dies of exposure on a night's winter exercise. So the regional commander made a practice of having everyone, every rank, spend one night in the snow with nothing but the clothes on their back. I've done it, too, in my Army days. You won't sleep well, and you'll wake up shivering several times, but you won't die if you stay off the ground, stay as dry as possible and out of the wind.

    1. Regards the Soviet Army, I read a non fiction intelligence report by a Soviet soldier of his experience in the winter of '41-'42. The army was short of most winter gear, boots, clothing, tentage, fuel, shelter. One of the methods used to overnite the infantry unit he was in was to take a long rope and everyone in the unit grasped it. Then the man at one end stood still and the unit walked around him smooshing everyone together. After an hour or so, the man on the outside end would stand still and the rest would walk around him smooshing everyone together. Don't think I could ever have gotten my guys to buy into that but Soviet discipline was a tad more harsh in those days.

  9. I spent December of 1980 living in my car. It was a big Ford station wagon. Thankfully I was near Houston, so not nearly as frigid as further north.

    I was working for a lumber yard and was able to pick up damaged 1" thick sheets of foil backed foam board insulation. The very first one went under my mattress in the back. Additional pieces went in all of the windows in back. A second one went under the mattress when I got another large sheet. I also put one between the folded down rear seat and the front seat up to the headliner.

    The insulation under the mattress had a very significant effect. Some condensation issues, but the foam board on the windows helped that a lot.

  10. Years ago I did some winter camping on my favorite ice fishing lake about seven miles off the road. I have been out at -30 in a pup tent with a closed cell foam pad and a cold weather mummy bag. I did fine, caught fish and made it home in good shape. Insulated coveralls and parka, leather mitts with replaceable liners and spare liners in the pack. I was hauling it on a three dog sled the one time and snowmobile another. Fur lined hat. In a survival situation I would hope for a full bodied spruce to hole up under on a bed of spruce tips from a different tree, never had to try it. For what it’s worth you can die of exposure well above freezing. When I was a kid growing up on the south shore of Long Island, N.Y. there was a story about a couple teens who went sailing in a little one mast open boat with no oars or motor. It was May with few boats, long before cell phones and they were becalmed out in the middle. They only had swimsuits and a light top on and apparently they were not missed. They were dead the next morning by the first clam digger on the bay in no colder than 40’s weather on a clear night. I met the guy that found them a few years later when I was learning to dig clams to pay my way through college. He was never first out on the bay again!

    1. The winter camping was near Delta Junction, Alaska.

    2. The winter camping was by Delta Junction, Alaska!

  11. Pretty much every real world expert has, at one time or another, stated the same ‘sleeping outdoors in the cold’ maxim – “you need a lot ‘under’ you, not much ‘on’ you, and a moderate amount ‘over’ you”.

    My ‘worst’ weather experience (carrying/pulling my own kit)) was -51F (+ wind chill) in The Northwest Territories, although I’ve regularly slept in -30F (+) in Abisko and around Utsjoki (northern Sweden and Finland). And … I hate to disappoint you but … you pretty much nailed the priorities.

    When moving, sweating (paradoxically in such conditions, overheating) is ‘the’ killer and wool is ‘king’. Merino base layers are now common, but the locals and real experts are now returning to wool as insulating layer and even outers – I have worn Swanndri shirts/smocks and Dachstein sweaters and gloves for decades, but have been wearing Micklagaard Abisko smock and Pro pants for the last few years (sometimes under a Lure of the North smock depending on weather and activity). Even my boots are either Lundhags (ski) with felt inners, Nokian Naali rubber boots (with felt inners) or in the most extreme, Steiner Yukon Mukluks. Wool breathes, and still insulates 80+% even when wet.

    Sleep systems are big, bulky and heavy (no matter what you use) so wool is not really used much (although I do use a canvas/wool sleep mat cover by Outhaus). I use a base of a Savotta (Finnish military sleep mat) then an expedition weight self-inflating mat (by Multimat in the Outhaus cover), with a -30 sleeping bag inside a Jerven Fjellduken Kingsize (I’ve slept on the Savotta, inside the Jerven, just wearing my normal clothing down to -25F in complete comfort – those two are the complete Finnish Border Guard issue system). Snow is actually fine to sleep on as a poor conductor (as long as you don’t melt it) but beds of pine/spruce branches (as deep as you can make them, 4” absolute minimum … compressed) or even a full wood/leaf bed (a la if remaining in place for a time is better. [pallets, in urban areas, if you block off the outsides to prevent air movement underneath, are really warm/comfortable - don't ask how I know!].

    Priorities (as you said) are: 1) Insulation from the ground; 2) protection from wind and weather; and only then does ‘comfort’ of insulation need addressing (in most situations I’ve found, cover those two areas and you can sleep with what you were wearing without issue with maybe adding a blanket).

    If I found myself sleeping rough I’d like my Savotta/Jerven kit (I don’t go anywhere without my Jervenbag original on my belt, or Thermo in bad winters, and a Sea-to-Summit insulated pocket sit pad – add in a chemical hand-warmer, as an area/shelter warmer instead of the ubiquitous candle, and you’ll ‘survive’ almost anything nature can throw at you - and it really annoys/impresses SAR when they have to wake you up from a comfortable sleep in the middle of a blizzard, again ... don't ask!).

    1. Good source of Finnish Army Surplus, and more

  12. Not mentioned yet: Don't hit the booze or other judgement-altering drugs.

    Alcohol increases the blood-flow to the surface. It will give you the sensation of being warmer (that is where most of the nerves that "sense" warmth are) but it will disrupt your body's finely tuned run-in-degrade mode and suck heat away from the most critical organs...which includes your brain.

    You need to have your wits about you when you are in an environment where small mistakes can kill you. The wrong kind of paranoia is bad. The right kind of paranoia is good.

    Yeah, maybe your situation sucks but it is temporary. Getting drunk or stoned or trippin' on psychodelics can make it permanent.

    I have no opinion on tobacco except to say cold is a stress on your heart as shutting down surface capillaries tends to increase blood pressure. Smoking is also a stress on the heart. If you might have heart disease, go easy on the tobacco. The good news is that you won't need the smoke to keep the mosquitoes away.

  13. Maybe I missed it, but a wool hat - watch cap is a big big deal.

    Keeping the heat in the noggin is good and It kind of cushions the head on a bumpy surface.

    1. Agree +100.

      As someone who is "follically challenged" (and have been since my twenties, Sigh!) I have more hats than maybe I should - everything from purely wind-stopper types for high activity, right up to heavy weight "balaclavas" and beaver-fur trapper types. The most used are a wind-proof issue watch-cap, and a wool ball cap.

      The thing I have noticed though is that it's not 'just' the head, it's the neck too. I have always carried, and worn headovers/neck-tubes/Buff's any time I've needed a hat. the difference they make is ... massive.

      Then there's socks too ("If your head is cold, put on ... another pair of socks" is one of those weird, but true, old sayings).

      There was some research done decades ago, where a bunch of recruits were tested in the lab. The first group got to wear full thermal clothing but without hats, gloves or socks. The second got to wear the opposite, 'only' hats gloves and socks (and boxers too FYI). Guess which group coped the best with extreme cold? That's right, group 2, go figure.

  14. My physics teachers weep for you EJ! Heat is the flow of energy from a high temperature to a low temperature. It flows in all directions.
    I have spent a few weeks in November in northern BC including a few nights rough camping in the bush. We had to keep a fire under the Super Cub so the oil wouldn't thicken .
    Typically I stripped to my long johns, pair of silk socks and a wool cap. Slept in a mid range bag with a flannel bag liner and we all typically woke up with a frost beard. We all had a plastic or canvas ground cover and a foam backpackers pad. Some used their horses saddle blankets as extra insulation.
    Northern BC does not have any decent fire wood, it was all spruce or pine and the fire would go out sometime during the night.
    If we got stuck out and could not make the cabin, we would make a snow wall to block any wind. As I recall the coldest nights were dead calm. A bed of spruce or pine boughs under the ground sheet made quite a difference.
    A side note was the cold never seemed to bother the horses. I was told the rancher brought 90 head of horse north with him his first year and all but 7-8 died that winter. Those that survived became the breeding stock for the ranch.

    1. When the Oregon Trail first opened up, there was a brisk business in writing pamphlets for the Eastern folks to read to prepare them to survive in the wild, wooley, west.

      One of those pamphlets advised folks to hunker down in rivers and lakes when a blizzard approached because it is a proven fact that liquid, fresh-water never drops below 32F while the air of a blizzard might be -40F. All (mostly) true.

      In real-life, it was very bad advice because it did not comprehend the thermal conductivity of water, the specific heat of water on a volumetric basis nor did it comprehend the energy penalty for getting body-and-clothing un-wet.

      The advice may have looked great on paper in Cambridge, Mass or NYC but it failed in the field.

  15. Our Physics teachers didn’t mislead us and the laws of physics haven’t been rescinded. It all boils down to systems (our hot little bodies and the big cold environment) constantly trying to reach equilibrium and the three methods of heat transfer: conduction - this is the one working between you and the surface that gravity is holding your sleeping body to, convection - the reason that moving air or water saps so much heat so quickly, and radiation - or the emission of heat through electromagnetic waves. A good sleeping pad for conductive heat protection, a high loft sleeping bag that fits as closely as possible to your body for protection from both convective and radiant heat loss, and a defensively selected sleeping site and tent to protect against convection. And the best way to amp up your sleeping game after you have addressed the Big Three - sleep in warm dry clothing and wear a warm hat to bed. If you’re shivering through the night - you’re losing the battle, and in a cold environment you don’t want to have to try to drag yourself out of a deficit situation. Stay well fed and hydrated. You need extra calories in cold weather above and beyond what you would need to perform whatever “work” you are doing.

  16. When I was at sea a tech named Gino from Quebec told me his stories of dealing with the cold. He was into survival tests. There is likely a genre of extreme sports names it goes by but I don't know what it is called. He would sleep in snow caves, etc to prepare for treks alone across wilderness in winter. Mental preparation was also key. He read philosophies on dealing with and accepting death in gruesome scenarios. His next big trip he hoped to do was to cross Ellesmere Island alone. That is close to a death sentence if done wrong. Beside the elements, polar bears were a huge threat. Gino was an interesting cat and I often wonder if he did Ellesmere or what happened to him.

  17. The physics rationale though is that the insulation under you is not as good as the insulation over you, because of compression of the dead air spaces. Heat usually (but not always - water approaching its freezing point becomes less dense, which is why ice forms on the top of the water and floats) creates less density, and so natural convective buoyancy will cause warmer matter to rise in a gravity field. But heat flux will always be higher in the direction with less insulation and a greater temperature gradient. The ground is a better conductor than the air, so if you only have one blanket, sleep on it, not under it, if the ground is cold. Wind (forced convection) may alter that.
    And a hat helps because your head has more blood flow and is warmer than the rest of your body. So the greater thermal gradient on your body surface is likely to be at your head (and neck).

  18. I always change into fresh skivvies before bedding down in winter. The day's clothes have sweat and will be cold and clammy at night. The watch cap is key for sleeping warm as are dry socks.

    One of your commenters linked to the Crimean Oven. I plan to try that when I can with some pipe.

  19. Fifty years ago 4 teens got stuck in a snowstorm in their four wheel drive vehicle on a power line in Massachusetts. They kept the motor idling, to keep the heater running. Drifting snow packed up around the vehicle, keeping the exhaust under it. They were all found dead the next day, from the carbon monoxide. Winter ignorance is tragedy awaiting. Great posts here.

  20. In Muskegon:
    Nobody has said anything about using vapor barriers in sleeping bags or other cold weather applications. You can’t sleep in a bag for too long without saturating the outside with moisture. After 20 days or so, the vapor from your body will start freezing deeper and deeper inside your bag… it’s important to dry them out if you plan to sleep in a bag long term (7+ days). Vapor barrier socks, pants and shirt trap the moisture closer to your body, it’s not comfortable for some, but wearing light thermals underneath might help. In the morning, hang them to dry. Trash bags can be used in a pinch. It keeps your winter bag cleaner and functioning better for longer.
    Also research a Palmer furnace… and I can’t remember all the other terms like it.

    This is all from research, not personal experience. Take with adequate salt… and some butter before jumping in bed!

  21. In Muskegon:

    See also…

    I recently found these and a few others between not seeing any deer. “Warm the person, not the space!” - search for that!


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