Tent condensation manifests itself either as frost on the inside surface of your tent or moisture droplets that are transferred from the inner tent to your clothing and gear. It is undesirable, particularly in winter, because it can make your gear wet and degrade its insulating properties
Here are a few camping tips to limit the amount of condensation buildup in a single or double-wall tent.
Vent Your Tent
The best way to prevent moisture from building up you tent is to help it escape by venting your tent. If your tent has a front door and an inner bug screen, you can unzip the outer door fully and still prevent snow from coming inside by keeping the screen closed.
Alternatively, if you side vestibules, it’s best to open both of them up wide to prevent frost build-up inside. In my experience, venting through a smaller hole is far less effective at reducing condensation or frost build-up.
Don’t Cook in your Tent
If you can avoid it, don’t cook or melt snow in your tent. This only turns it into a Turkish Steambath. If the weather is just too crappy to avoid this, try digging a hole under your tent’s front porch, if you have one, and cook inside it with the door to the tent closed behind you.
Don’t bring snow into your tent
If you bring snow into the tent, you are significantly upping the chance that it will melt and increase the internal humidity in your tent. Brush all snow off your boots, back, ropes, and gloves before you get in the tent. If you have a vestibule outside the main door, leave all gear that doesn’t need to be dried there. If you bring snow into your tent despite these precautions, carefully sweep it out.
Don’t exhale into your sleeping bag
It’s tempting to put your head inside your sleeping bags on those long winter nights. Don’t do it. Keep your face clear of the bag and avoid exhaling moisture into your insulation. You can exhale a liter’s worth of water at night: not only will it degrade your insulation, but you’ll have to carry it all the next day as extra backpacking weight if it remains trapped in your bag.
Dry out your sleeping bag in the morning sun
If it’s sunny in the morning, open up your sleeping bag and dry it out in the sunlight on top of your tent. Many down sleeping bags have darkly colored interiors for just this purpose, to absorb as much of the sun’s radiation as possible and accelerate drying. Bringing a wet or damp sleeping bag back into your tent on a subsequent night is not desirable because it will create condensation and retain less of your body’s warmth.
Put Wet Gear into a Stuff Sack
Don’t try to dry large items such as pants or a sweater in your sleeping bag at night. Instead, put them into a stuff sack, close it, and stuff it in your sleeping bag to keep the contents from freezing. If necessary, you can dry these garments using your body heat by wearing them the next day.
Those are some basic tips to stay dry in a winter tent. If you can recommend any others, please leave a comment.
Good Post! Condensation reduction will also require a circuit. Generally, this is made by opening the perimiter vents fully as well as the upper vent. In very cold weather, below 20F, the tent will not hold enough heat to make this work. Soo, suplimenting with a candle lantern hung near the peak or the highest venting area will help, too. Heavier but worth it for three or four day hikes. This pays about 1/3 of itself after in keeping condensation down in the tent, bag and helping to dry cloths.
Also, a bandana for cleaning out the snow and wiping the sides off in the morning help. A light weight option.
I agree in very cold weather you can only limit condensation, not prevent it. I remember one night in the Adirondacks where it was -20F. We were in a Nemo Tenshi tent. We had all vents and windows open, and we even had the door open! We still had a fair amount of frost accumulate. There was even frost accumulated on the mesh bug screens.
Actually, I find that sleeping alone, without partners greatly cuts down on internal frost/conditions, even in much warmer temperatures, since less people vent less water vapor.
It even makes sense, weight-wise. It seems like a lot of three person tents weigh 8+ pounds, while you can get a single person tent weighing 2-3 lbs. I'm testing an even lighter one now, that weighs under 2 pounds for winter mountaineering use. Of course this only really matters if you're going to be out a few days or more, and you like a down bag.
Marco – understand with candle. I am very conservative however with open flames in tents. If they catch fire, you're going to get very hurt, and tents these days tend to be very flammable. Like smoking in bed.
Yeah. Open flames are not real good. But a candle lantern works pretty well (enclosed flame.) Really no worse than having a heater in your house (enclosed flame.)
Typically, your body heat amd your body's water vapor are at odds with condensation, itself a product of dewpoint: internal (to any enclosure) and external conditions. A ventilation system includes lower and upper vents. Wind and/or heat drives the air exchange, leading to a dryer enclosure. Additional water vapour is added from your body through perspiration (insensible, and, normal through heat regulation.)
1) Maintain good ventilation (some heat source to suppliment body heat in very cold weather.)
2) Maintain reduced moisture generation by sleeping cooler.
You have covered most of the others. A floor will help, too, but this was covered.
Macro and Earlylite, I use a candle lantern too, in extreme cold.
I made a simple reflector/deflector from a piece of aluminum flashing which I hang over the candle. This helps reflect a lot of light down to where it’s needed. It also absorbs the intense heat directly above the candle and re-radiates it down to where I’m sleeping. This protect the tent material from overheating. I hang it from an internal clothes line so the flame is about 8 inches below the tent ceiling.
The candle lantern really does get a good stack effect (chimney effect) going in the tent to carry away the moisture with a small high and small low vent. With a good chimney effect, I don’t worry about the possibility of carbon monoxide. as a home inspector, I have a very sensitive portable CO detector and used it overnight with the candle a couple of times. I have never detected any monoxide in the tent. But be sure you KEEP VENTS OPEN!
To make my reflector, I just punched a small slot at the apex of a piece of roofer’s step-flashing. It’s 4 x 8 bent into the shape of an “L.” It folds easily and stores in a small Ziploc (to contain any soot). it slips over the little loop in the candle lantern wire bail and I clip it in place with a mini biner. the biner, i feel, is important also as a heat sink so the candle handle or a smaller hook doesn’t conduct enough heat to melt through a nylon hang loop in the tent. you can chain a couple biners together to get the elevation and deflector angle you want.
You could make a reflector from any piece of flashing, pie tin or the aluminum bottom of a cocoa can, etc. If you are using aluminum flashing for a stove wind screen or a pie tin under your stove, that could double for a candle reflector.
Just position the candle such that you wont knock it with your head if you sit up suddenly when the wolves or coyotes start calling 50 yards from your tent!
Pro tip: the candles usually last 8 hours. You need the heat most in the later half of the night. So I don’t start mine until my first pee call at about midnight. I lite the candle before leaving the tent and it helps me navigate back if I get disoriented. Then it burns on into the coldest hours before dawn.
I’d love to see a picture of this if you wouldn’t mind?
I've given up trying to prevent condensation. Since I'm a very still sleeper I don't bump the walls of the tent during the night and when I wake I use a pack towel to pull the condensation off the tent walls. Capitulation? Sure, but it works.
hey. great site, great articles.
i've had good luck freeze drying clothes to a certain degree outside, overnight if it's cold enough. usually only if they are damp and it will be warm enough in the am to put on freezing cold clothes.
Interesting post. I'm wondering though: Ventilation works on the principle of moving the humid air out, which is obviously good to prevent condensation, but means that you can't really maintain a higher temperature in the tent than in, say, a tarp. In principle, by simply heating the air enough, there would be no condensation either since warmer air holds more moisture. But that it not exactly easy to achieve. As to the candle idea, I can see where Marco is coming from, but does it really achieve more than opening vents a tad more?
As to the stuff sack and wet clothing. My hypothesis is that body-drying damp clothing will not significantly increase humidity as long as we're talking fairly few pieces … a pair or two of socks or similar. Exhaling releases so much moisture that I think I couple of socks won't significantly change the balance (?). Freeze drying works quite well IMO, but it's slow. In other words, it seems to me there isn't really much than can be done, ultimately?
This whole freeze drying tangent seems far-fetched. Put your socks on your belly and they'll dry by morning.
I used a double walled, 3 season tent with a lot of bug netting below tree line for the past few winters. I had to build snow walls to limit snow from blowing under the fly and in through the mesh.I had to watch out for excessive snow accumulation as well. But the big advantage was very very little frost condensation [typically none].
This winter I am using a hammock and tarp. When there isn't a lot of wind I can arrange the tarp with a generous gap at the lower edge and there is little condensation. When the tarp is set-up like an A frame tent I do get some condensation but it stays as frost on the tarp.
The drawback for both the hammock and 3 season tent is that the internal temperature is almost the same as the outside temp. They act as wind screens but retain with little heat. So moisture from my body is evident as frost on the outside of the sleeping bag.
Trade-offs….
If you sleep outside in winter, I don't think you can expect a shelter to keep you warm. That's why you pay western mountaineering $600+ for a good down bag. Your shelter is really just there to block the wind/snow and provide psychological comfort.
So, what kind of hammock are you using this year? What's your winter insulation system look like?
agreed
Wow. Live and learn. I just prematurely left a mid-November section hike of the Connecticut section of the AT…I’ve never cold weather camped, and lack of insects and people sounded too good to be true! And as much as I wanted to stay, I had to leave because I screwed the pooch on various issues. My tent is a three year old Tarptent Bowfin 1.weather conditions called for rain, sleet, high winds….temps in the low 20s. Where did I mess up? Let me count the ways (1) I closed both vestibules. (2) I located near running water in a low spot. (3) I didn’t bring a towel. At 0400, I woke to sleet, and aining both outside AND inside my tent. And (4) I had my head buried deep in my brand new Thermarest Oberon 0 degree down sleeping bag. When daylight broke, my sleeping bag was damp and my tent seemed soaked through. Concerned that the next few nights were colder, and the forecast didn’t appear to be conducive to drying my gear…I called the wife in western Massachusetts to come pick me up. I was initially disappointed in my Bowfin 1…..when all along, the primary culprit was me! Again, live an learn.
Sorry that didn’t work out. November on the Northeast is just a sucky time to backpack. Not enough daylight.
I sleep in a hilleberg nallo, and its only in windy weather, I have no condensation in the morning. If I use the bug netting, it seems only to freeze up, and leeve no holes for ventilation. The past days I tried out to leave the door fully open, and it helps to keep the innertent free of ice, but still my sleepingbag feels damp on the outside in the morning. And also has small partickles of ice close to the outer fabric (inside).
I tried to cover up with a bivy, but it just ends up damp between the bag and bivy.
Im out of ideas, or maybe a curtain like the nemo tenshi is the way to go?
@Earlylite, re freeze-drying. i was talking about the big items that you wouldn't want to try to dry inside your bag. pants/shirts, etc
i hang my laundry at home when it's not raining and i did it once in the whites when it rained that afternoon and froze overnight, worked well for my wet pants (didn't have rain pants).
your mileage may vary
There are a number of folks here that have had much more experience than I hiking in cold and snow, however "freeze-drying" hasn't worked for me. I have attempted to hang damp/wet hiking clothes in cold (teens and below) weather and I ended up with nothing more than frozen clothes. I can't say that some moisture didn't evaporate prior to the freezing but would assume that the process stopped as soon as the moisture turned into a solid (ice)? I have seen pictures of folks hanging clothes in the high mountains and assume that wind and sun will cause evaporative drying before freezing. My trouble is I usually stop walking near dusk, and the freezing seems to occur very quickly when I hang the wet clothes, which is often just before or just after sundown.
I can say that I am absolutely sure I prefer putting on damp "warm" clothes in the morning vs. cold frozen clothes. Clothes stored in my sleeping bag in a silnylon bag are easier to put on and start evaporative drying immediately when moving. Frozen clothes can be virtually impossible to get on (and require an act of faith and a pep talk to attempt), then must warm against my body and turn the solid back into a liquid before evaporation can begin (at least I assume so).
Obviously on a sunny day, wind and absorbed heat will have an impact but I am not sure about the gains on a multi-day trip with little camp time during the day.
My only experience with "freeze drying" clothes came about 35 years ago when my dad and I canoed Santa Elena Canyon on the Rio Grande in Big Bend National Park. I got thoroughly doused by the standing waves at Rowdy Rapids. I hung my wet clothes outside the tent and they froze solid in the 18°F overnight temperature. At dawn, I beat the ice out of them and they were almost completely dry, if not a bit on the chilly side. My father said he had to pour a half dozen cups of hot coffee down my throat to coax me out of the sleeping bag that morning. What likely got me going was having to take a potty break after all that coffee.
To freezedry clothes, the air needs to be very dry, and the clothes needs to be thin.
Dont think it will work with a heavy wet woolsweather.
Layer up..
Freeze drying can work. When temps are quite low (~10-20F) and the humidity is near 0, water will siblime off, directly, from ice to water vapour without the intermediate water phase. In the north east, these conditions are rare. Mostly confined to the downwind (usually the eastern) side of 4000' hills. If your cloths are only damp from sweat, hanging them out, really spread out in a known dry area, not in your tent, can dry them overnight.
In a fairly constant breeze you can do the same. Again, keeping the cloths dry is paramount, since they will dry slowly. Not real good for wet stuff, since our conditions are not like the very dry chinnook winds (Santa Anna Winds) they get out west.
The more traditional drying by the fire works better, though.
The best thing to do when hiking is make sure you are not overheating by managing your layers. If you are at a comfortable temperature, you are probably sweating. Hiking a little cold pays off in the long run.
Drying stuff in your sleeping bag works only for damp clothes (socks, gloves). If something is soaked I would not try to dry it in the bag as it will impart alot of moisture into your bag. I would however put it in a plastic bag and store it in the sleeping bag so it doesn't freeze solid. This way it may still be wearable the next day.
Dark color sleeping bags/clothes can warm up and dry suprisingly fast in the sun – even in very cold temps. I always buy sleeping bags with dark interiors for this reason. Hiking in wet clothes can also dry them out with body heat, as long as you are not continuing to sweat and they have alot of airflow.
Generally speaking, I never have a fire when winter camping as I'm generally not going to spend the time and energy to make one.
You beat me to it shane. Drying clothes in the sun works wonders. No sun, build a fire, if you can, in front of a rock wall or a hand-built wall of snow. You can also line up sticks to create a fence. The fire will reflect the heat back at you and dry anything you have hanging. Hard to find wood though, under 6 feet of snow.
Mind you, carrying waterproof pants and using gaiters would have helped ward off the problem in the first place. Your mileage may vary, but this seems like an oversight.
I have dried clothes (and sleeping bags) in the sun in very cold conditions and it works great, but my comment was from my experience on the AT last year. We left Springer March 1st, and ended up walking 16 days in snow. Typically you end up in camp or a shelter around dusk, with damp base layers. I tried hanging clothes but had little to no chance at sun most of the time due to the clouds and timing. I finally gave up, kept them in the sleeping bag with me in a sil-nylon bag, and put them on damp when it was time to go. Walking them dry seemed like the best option, at least to me. I never saw a campfire until the days got longer- too much work and everyone goes to bed at “hiker midnight” anyway!
Okay …. newbie here. What is “hiker midnight”?
8 or 9 pm. sometimes earlier – last night it was 5pm (winter)
That got my attention, and I think it’s good advice. I have a long April 2 trip farther north and I will also probably encounter some snow.
What kind of shoes were you and the Rev wearing? I’ve been pondering my options, especially with spring runoff.
We both wore light boots for the first 350-400 miles (which because we bounced took us through the snow and into dry weather) and MLD eVent gaiters. I can't remember what RevLee wore, but I had Lowa Zephyr GTX boots because they were relatively light and were one of the few boots that really fit my feet. We both switched off to trail runners in VA (Salomon XA Comp) and that will be my shoe going forward except when dealing with deep snow. Not sure how I feel about trail runners and snow, but then again I haven't tried it. The lack of a margin of error scares me on a long trip.
One interesting thing was we had very strange Spring weather in VA last year and we went from 9 degrees to 92 degrees in a week. My boots were great until the weather got hot. Within two days I had a blisters on each heel AFTER walking 400 miles with no problems. We were in Virginia's version of the PA rock fields at the time which may have contributed, but I never had any foot issues at all after going to trail runners. I will probably use them everywhere except true "winter" conditions. Also- for me, SuperFeet inserts are critical with trail runners for support and to help protect your feet with the thinner soles. I know standard thought is to not use Gore-tex in trail runners, but I prefer it after trying it both ways.
Have fun on your hike!
Holofill II, Qualifil, etc. stays warm even when wet, unlike down. We discourage NW scouts from down bags for that reason.
Even on a showery day you can dry a bag or clothes, etc. under a tarp if you align the opening with the breeze and put the tarp on a higher rope than the objects to be dried.
Maybe you should teach them how to prevent down bags from getting wet. If adults can do it, surely scouts can, too. :-) Surely, this just requires a stuff sack and a decent tent.
There's nothing like waking up in a warm sleeping bag in a winter tent, unzipping and sitting up to accidentally shake the frozen condensation off the walls and down the back of your neck. Wakey-wakey!
Last night it was minus 9 celsius and I was sleeping in a 4 season tent. I did not vent at all. I lit the candle lantern and ran one of those battery powered tent fans and for the first time woke up with no condensation on the inside of the tent
Fantastic info doing the overland track thanks
“You can exhale a liter’s worth of water at night…”
Holy Cow!
Years working in the trades has taught me that drying is helped by using SOME heat.
What matters is air flow. Put your items to be dried in the windiest spot. Use your tricks that maximize flow thru the tent.
Warming incoming air using a lantern will drop its relative humidity significantly. As stated above, you want (relatively) dry air. Warm air is not required.
This was a great article! I’m working on a product to lower tent condensation. Could you tell me the source that you got “You can exhale a liter’s worth of water at night” from?
Thanks!
What would you do when night temperatures are 30f and humidity is high? I have woken to an unusable (flat) sleeping bag before, as the dewpoint was inside the bag. What do you recommended?
What is a flat sleeping bag?
A sleeping bag that has lost all loft due to the down being wet.
Sounds like you should bail unless you can get your bag dried out.
Some people recommend a synthetic sleeping bag in this case. So you don’t? You should be fairly known with scottisch winters I believe.
Some people probably would. What’s your point? Wet synthetic insulation is as cold and awful as wet down. If you have the catastrophic gear failure you describe, I’d bail.
That’s a great point, Philip! Plenty thanks for giving your view, which helps me putting synthetic solutions in perspective.
Have a 4 season tent and have tried a candle lantern and vents with door open and still wake up to frost on the inside. Less with the candle lantern but only about an 18″ diameter circle on the ceiling of the tent was frost free, walls and sleeping bag still nice and frosty. Will continue to experiment with different options but really haven’t found anything to help. Maybe a vapor barrier liner and a bandanna over my mouth would work to reduce water vapor. Also wondering what type of battery operated light weight fan would be best to move air around?
Try camping someplace with less humidity. Like avoid anything near an open or running water or overhead vegetation. I usually avoid all frost of I keep my door mostly open.
I once was winter camping in the same spot for 3 nights. I absolutely froze the first night and frosted… I was up far too early drinking my hot drink and walking around to get warm and found a spot only 30 feet away with no frost on the ground… I set my tent there the next two nights and was warm all night… to this day I wonder if I moved to a uranium patch…
Camped in a field last night at 15°F. Had the roof vent fully open and the front door vestibule halfway open. I still woke with a heavy layer of frost inside of the tent. I would like to get this figured out for myself before the really cold weather settles in. Tonight I will try with the front door fully open.
Hi. I just wanted to say that for the second time I was in a freak warm up to upper forties, with rain, and 6-12 inches of snow melting overnight. The interior was soaked… even between the thermarest and sleeping bag. It was a two person copper spur. I just don’t recall condensation ever being that bad in my rei passage. Does ultralight material have condensation issues more that other material?
Sue – you should read this – it’s a very comprehensive explanation of condensation and how to minimize it.
https://sectionhiker.com/backpacking-how-to-prevent-tent-condensation/
Thanks! Read it already!
Sue, an old thread here.
Anyway, yes, a UL tent can be more condensation prone than a heavier, polyester one. Each material will have it’s insulating value or R value. The better the insulation, the lower temperature gradient between inside and outside. So, you get slightly less with thicker polyester fabrics than UL nylon fabrics. But, I don’t think this is enough to count on over general conditions. Wet, humid air at 100% humidity, adding more moisture at 90F+ with your breathing, cold ground in the neighborhood of 32F, additional moisture from ground fog, that rapidly cools on any surface near the ground is a recipe for disaster. You will be soaked by morning. Sometimes you simply cannot avoid it, despite a well ventilated tent.
Good to know About the rf values. I may go back to single person one door not ultralight. I got a two person to reduce condensation, but it seems to have not helped a bit… I think you are right and under those kind of conditions it probably doesn’t matter what you do. Still, it seems the tiniest rains result in condensation with this tent. I think it may be worth it to go back to the heavier tent material. I have been in some cold wet snowy conditions in my rei passage and not awakened to a soaked sleeping bag! Moist a little but pales to what happens with my ultralight.
I’d imagine that there is some absorption at play. Heavier materials can absorb some of the condensation so it doesn’t all end up on you… just a thought.
any experience in adding a zippered mesh window to a single layer winter tent? Interior frost/water droplets, no matter what I do works (camp under trees, open the door, open the ventilation window, store wet gear in stuff sacks, etc).
no sorry, although I do have a single wall winter tent and I also sleep with the front door and rear window open which does help.
Not to derail, but I came to this thread with a different question in mind. The winter sleeping bag itself. Many options: Regular outer fabric? Windstopper outer fabric (Western Mountaineering)? Vapour barrier liner? If the goal is to keep the bag dry from both the body (and the damp socks being dried on the belly) and frost falling from the roof, what are the systems that work over multiple day trips?
Read this.
https://sectionhiker.com/sleeping-bag-gore-tex-shell/
I don’t usually go camping or hiking, but your article on preventing tent condensation in winter made me feel like I was right there with you in the great outdoors. Your tips were so helpful and informative, and I learned a lot about how to stay warm and dry when camping in colder weather.
I especially appreciated your emphasis on ventilation and airflow. It makes perfect sense that keeping air moving through the tent can help prevent condensation from building up. And your suggestion to use a bivy sack to keep moisture away from your sleeping bag was brilliant! I never would have thought of that myself, but it seems like such a simple and effective solution.
Overall, I just wanted to say thanks for sharing your expertise and experience with us all. Your passion for the outdoors is contagious, and I feel inspired to get out there and explore nature myself. Keep up the great work, and happy camping!