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I recently purchased a Marmot Women's Mavericks 15 mummy sleeping bag thinking it would keep me warm here in North Florida. I tent camp with my son's Cubscout Pack, and I just put the bag to the test this past weekend. We estimate the temperature got down to around 30 degrees. There was no rain and no wind. When it was time to hit the hay, I started with two layers of long johns, one silk and one cotton, and quickly had to put one more layer on. I added a set of sweats. I did fall asleep for a short time, but woke up shivering and had to put on my ski jacket. I'm pretty sure my ski jacket has some kind of Thinsulate or equivalent insulation, and I was able to stay warm through the night, more or less. I was wearing a fleece hat, and had the head part of the mummy bag was totally closed. I was very disappointed in having to put on my jacket, as I thought the investment in this bag would eliminate that need. Thought I was doing all the right things with the layers. The top piece closest to my skin was actually a Patagonia Capilene top. My bag was on a Thermarest Z-lite sleeping pad which was in turn on top of an inflatable air mattress. ( I know, the air mattress is probably a no-no, but I'm going to give that up as a last resort.) My Coleman Sundome 10x10 tent was pitched on top of a blue tarp. What else can I do? Put my mummy inside of another bag? I also don't have a lot of "natural" insulation. I'm a slim gal, 5'7 and about 130 lbs. Any advice on layers, etc would be welcome. Thanks.


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First thing that comes to mind - did you wear to bed ANYTHING that you had been wearing during the day? That includes bra, panties, & socks.


If your answer is yes, than that was your problem. You should remove ALL clothing before bed & put on ONLY clean, dry, clothes. The sweat in any clothing worn during the day will evaporate during the night & chill you to the bone.


30 degrees is actually not to bad, at least not to those of us from northern Illinois! I hate to have the mummy hood closed. I toss & roll so I have on MANY occasions awakened to find the sucker flipped around & over my face. I will put on fresh sweat pants with a hoodie & clean, warm socks.


The ratings on bags are not always accurate either & can be affected by a variety of conditions. Having a sleeping bag liner or a fleece blanket to toss over helps.


Last thought - Get rid of the air mattress. The air is not a good insulator & might actually have helped to make you cold. If you want more padding add another sleeping pad.



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One thing to add to SN's post. DO NOT, in preparation for a good night sleep, roll out your sleeping bag or layout your PJs prior to actually needing them In doing so, they will stay dry and not soak up any humidity in the air that can also lead to a chilly night.


I have a summer tent and a winter tent. The summer tent is huge, I can stand up to change, it's basically keeps the dew and mosquitos at bay. My winter tent is a more of a puptent, like SN said, less area to warm with body heat, more of a pain to change clothes in, but WARMER!!!



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Your 3-season sleeping bag should have been fine for your camping trip this weekend - its rated to 15 degrees and Marmot is one of the best companies out there for sleeping bags. I was out camping this weekend in the Manistee National Forest (Michigan) with my "3" season North Face and never got cold at all while sleeping - and I never use my sleeping bag in the classic sense (as a bag to crawl or zip in to) - I use my sleeping bag as a blanket (fully zipped open, though the foot box remains closed - its a tapered bag, not a mummy). I slept on my Thermarest classic with a fleece blanket on top of the pad as a sheet. I wore a knit cap, boxers and a long-sleeved t-shirt. Warm as toast all night.


Your post describes a few common mistakes made when winter camping. The first is that you wore one too many layers at the outset - stick with one layer only - the capilene is more than sufficient, but if you like the comfort (both physical and psychological) of fleece, then make fleece your one layer (assuming of course that you changed into fresh clothes before bed and weren't wearing what you wore all day.


The second is that you added layers when you started getting cold. The sleeping bags insulation works by trapping and keeping your body heat - by wearing more than one layer, you actually worked against your bag by preventing your body heat from warming your bag up - and adding layers of clothing just gave your body even more surface space (in the form of all the extra air pockets - thousands of them) to heat up - which is also, incidently, one of the reasons you started shivering so much - your body was trying to generate extra body heat to heat the space around it. Shivering is the mechanism the body uses to generate additional heat.


The third mistake was wearing a hat in your mummy bag with the hood closed - now I know that seems counterintuitive, especially when one of the truisms of winter camping/hiking is that when you're cold, put on a hat. I wore a hat when sleeping but I wasn't wearing the hood of my bag (it was used as a blanket) so my head was exposed. In your case, the hood of the sleeping bag was your hat, and quite sufficient for the job. By wearing a hat under the hood, you can start to overheat, which leads to sweating, which of course leads to feeling even colder as the sweat starts evaporating off your body (we all sweat to some degree at night).


Fourth, as you already mentioned and figured out, the air mattress was also a culprit - the air in the air mattress sucked up a lot of heat - the thermarest couldn't ever hope to keep you insulated against a pocket of air that big that was continuously cold. Thermarests are a closed cell pad with many small pockets of air that get warmed up as you lay on them and remain warm because they have little exposure to the outside (thin sides with you on top and the ground on the bottom - the ground can be frozen and you'll still be better insulated with just the Thermarest). Once the first half inch of the ground is warmed up some (by you and your pad laying on it), the pad doesn't need to work as hard to keep you insulated from the ground - unfortunately, that just does not work with big pockets of air. Thermarests, in my experience, are more comfortable than an air mattress anyway - I've slept on hard rock with them and never felt the rock - you can blow extra air into the pad to make it a little thicker - you should really try it without an air mattress sometime - heck, do it on the floor at home as a test - I think you'll find you'll like it (and can leave one more piece of equipment at home).


You didn't specifically mention socks but I'm guessing you wore them - again, a counterintuitive thing but don't wear socks - the feet are one of the areas that sweat the most - even at night - socks - no matter what kind, in a sleeping bag, will retain that sweat and will start to cause the chills.


Try your bag again on another campout and try the suggestions some of us have posted before giving up on the bag - to summarize those suggestions:


1) Change ALL clothes before bed

2) Wear one layer

3) Don't wear a hat if using your mummy's hood.

4) Don't wear socks

5) Ditch the air mattress - use only the thermarest (and don't use just the air mattress instead of the thermarest - no matter how you slice it, the air mattress is bad for winter camping).

6) Don't lay out your bag until just before use instead of when setting up the tent. A note though: Think of Just Before Use as 1/2 hour before bed time - unstuffing the bag a 1/2 hour before using it gives the insulation in the bag a chance to recover from being stuffed into its sack - the insulation fluffs up which means it will work better - getting in to the bag right after its unstuffed can help to keep the insulation in the bag from working properly.


Hope this helps,



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In know you don't want to hear it, but you're going to have to leave the blowup air mattress at home. It's a very efficient heat transfer devise. The convection currents carry all of your heat to the cold ground.


Rather, get a Thermarest Pro-Lite 4. Very light, very warm and very comfortable. Combined with a closed-cell pad, like your Z-Rest, you'll sleep warmer and not be at too much a loss for comfortable padding.


- Oren


BTW, both of my Marmot bags (one three season and one winter expedition) have kept me very warm in many different conditions.

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Calico did a great job explaining how to sleep in cold weather. Perhaps I missed it, but here are two more suggestions. When you do get your bag out, shake it and fluff it up. The insulation is packed down, especially if it has been packed in a stuff sack or compression sack. It will fluff to some degree on its own. But pick it up and really give it a good shake all over for maximum fluff. If the insulation is packed, it can not insulate as well as when it has all of those little pockets of dead air space. Also, don't cinch the hood completely closed. Leave at least a small opening for your nose and mouth. Breathing into your bag does the same thing as sweating in your bag. When you breath into it, you are pumping it full of moist air that ultimately will make you sleep colder.

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Calico gave a great explanation. I will disagree with or add to a couple of his thoughts.



First, wearing clothes to bed. It took me years to listen to those that told me that "less is more". I kept freezing at night, even putting on clean dry layers. Now, I don't sleep with anything other than underwear from the waste down. To buy into this, you have to understand where your body heat comes from. It's primarily generated from your muscles. And, for most of us, the biggest muscles are in our thighs. If you cover them up with a layer or two, you are limiting that heat to only helping that area. Your arms, hands, toes and head have much less muscle mass, not near enough to generate the heat to stay confortable, so they need to share heat with your legs to stay warm. So, even though it is counterintuitive, wear less to stay warm.


Second, personally, I don't like putting my head inside my mummy bag. Breathing into it creates more moisture inside the bag, which makes you colder. I snug it up over my shoulders and leave my head out. I wear a wool cap to keep my head and ears warm. A little heat sneaks out of the bag, but that helps keep my neck and face warm.


Third, put more under you than over you. In winter, I'll use two thin pads. One is a thermarest and the other is a close cell foam. The two together get me up off the ground so that it can't absorb my body heat. I'll also often take my summer bag and put it under me to give me some more insulation between myself and the ground.


Fourth, If it's really cold, I'll take a small fleece blanket and line my sleeping bag with it. That will give you another 10 degrees of comfort.


Fifth, I'll toss a couple of hand warmers down around my toes. Now, you want to put them where you won't roll on top of them. I've done that. They get hotter than you think. But they give you a little toasty warmth around the toes.


Finally, Regarding your bag, don't keep it stuffed between campouts. Stuffing a bag compresses the insulating layers together so that they lose all insulating value. Compress it into the bag before your trip, and then lay it out and fluff it up a bit when you set up your tent. This will allow the insulating layers to fill back up with air, which gives you the insulation you need. One fall campout I nearly froze in 40 degree weather because I had left my winter bag stuffed from the previous winter. It makes a huge difference.


Best of luck. This is a great discussion.

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I feel compelled to offer some comments challenging several others made here about keeping warm.


Thermarest makes different kinds of sleeping pads. The roll up pad is open-cell foam enclosed in an air tight covering. Its basically a thin inflatable air mattress. The Z-pad is closed-cell foam. Closed-cell foam insulates better because the air in the pad cells is trapped.


Cold ground is a huge heat sink and will suck up unlimited amounts of heat from anything laying on it. A cheap conventional air mattress will not insulate much, though it is better than sleeping directly on cold ground. (Would you rather sleep directly on a slab of ice, or on a cheap air mattress on a slab of ice?) An air mattress does not make you cold. Cold ground makes you cold. An insulated pad separates your warm body from the cold ground, and that is the way to avoid losing body heat to the ground.


Comfort is part of a quality sleep experience. Being cold is uncomfortable, as is trying to sleep on rock-hard ground. A conventional air mattress may not provide much insulation, but it is comfortable. Using an air mattress for comfort, with a Thermarest or closed-cell pad for insulation is the best of both. The insulating pad should be next to the sleeping bag, just as Bizzy did.


Scientifically speaking, if a sleeping bag is wet with water it will cool by evaporation, but there is no way I know of that will cause it to become wet with liquid water simply by being rolled out. Humidity is gaseous water vapor in the air and does not absorb heat or make things cold any more that cold air does. However, a rolled up sleeping bag may retain some heat from the day. It may be warmer if unrolled just before crawling in. Unrolled early, it will lose whatever heat it had and be just as cold as the surrounding air. Personally, I get my bed ready when I set up camp, so I dont have to mess with it in the dark.


If a body is cold, it is because the heat the body generates is being lost to the atmosphere. A sleeping bag prevents that. Clothing prevents that too. Clothing provides insulation that traps the heat and holds it close to the skin. One layer is better than naked, two layers provides more insulation than one, and three layers provides still more. If you are cold with one layer, add another. The added layer may initially feel cold until it warms up, just like dressing with cold clothes in the morning. But cold clothes in the morning doesnt stop us from getting dressed. More clothes is warmer than less clothes.


If feet sweat during sleep, the evaporation will cause cooling. Evaporation will take place whether socks are worn or not. If feet are truly sweating during sleep it is either because they are too hot, or you have a nervous condition. If one has cold hands, you would not remove gloves because of worrying about sweaty palms. Likewise if your feet are cold, you would not remove your socks to warm them up. From personal experience, I can tell you that my feet are a whole lot warmer with socks than without. Wear wool or something other than cotton so moisture, if any, will easily pass through.


A hat helps keep your head warm by preventing heat loss. A knit cap works better and can pull down around your ears. A mummy bag with its built-in hood with drawstring does the same thing, and a wearing a hat or cap would be redundant.


One last thought. For years my wife suffered from being cold at night. It was later discovered she had a thyroid deficiency with affected her metabolism. After getting that corrected with medication, she was cured of being cold at night.

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I'd like to add a thought to what FScouter said (BTW, Great Job also, Calico). If you're in a tent, your greatest heat loss can be to the ground. I've found over the years that it's more important to make sure you have a lot of insulation UNDER you rather than over you. In our troop, we invest in 1" foamcore building insulation (4x8 sheets), cut them into 2x2 squares, and then connect them together with duct tape to make an "accordian fold" that is 2x6 feet. We put this under the tent where we sleep and put our pads on top of that. Really works well, and is pretty cheap to boot.


On a related subject, once you get into your bag and get it warmed up, try to stay in it until morning. It's very difficult to re-warm a bag once you get out at night and then get back in.


Now, I have to admit, I read your first post and wondered just how cold it could get in Florida, thinking in terms of up here in northern Illinois. But, everything's relative, I guess, and these winter camping tips work well regardless of what you consider "cold" to be in your neck of the woods. Winter camping can be the best camping there is if you know what you're doing.

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A few additional thoughts:


Regarding warming the air in the tent itself:

You don't want a warm tent. It encourages condensation on the walls. If condensation is severe, open up the windows. Tents don't keep you warm, sleeping bags, pads, clothing, etc... - those keep you warm. As mentioned by someone else, do not bring candles or heaters inside a tent.


Regarding sleeping pad insulation:

Open-celled foam does provide plenty of insulation so long as it is not overly compressed. A Thermarest pad can provide plenty of insulation ... so long as it is not overly compressed. To limit compression, you might blow some extra air into the Thermarest to make it a bit harder (to avoid overcompression). An even better idea, as mentioned by others, is to place a second FULL-SIZED closed-cell foam pad underneath the Thermarest. Placing insulation over the entire floor will certainly make moving around the tent more comfortable, but I've never done that.


Fueling the Furnace:

Before going to bed you'll want to make sure your body is generating heat, as it is the sole source of heat for keeping your warm at night. First, make sure you have something to eat - Fuel for the fire. Second, take a walk just before heading into your tent for the night - to get the furnace (and blood) running.

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Feeding Kenk's furnace is something we always did. We saved dutch oven coobler until right before bed to give the boys some warm carbohydrates for their system to churn away on. Another inportant factor is to cut down on the drinks before bed. One, hopefully you won't have to crawl out of your bag in the middle of a cold night to relieve yourself. Two, your body uses up a lot of heat trying to keep a full bladder warm. A full bladder will make you sleep cold.

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Good discussion!


I'm a big believer in socks. For cold weather camping, I stuff a big, thick pair of SmartWool socks in with my bag. The only time I wear them is at night.


I also pack a polypro hood in the bag. It weighs nothing at all and makes a huge difference. I prefer not to cinch the hood tight around my face.


When the weather's really cold, one of the tricks I use is to pull a dry shirt or sweater into the bag and place it across my body - forming an air dam to keep warm air in and cold drafts out. Again, this allows me to keep the top of the bag a little bit open to allow more movement.


As for body fuel (calories), a Snickers bar or two are great. Clif Bars, too. Your body needs the calories to keep your heat up.


Some friends swear by filling a Nalgene bottle with hot water and sliding it into the bag just before climbing in for the night.


Speaking of bottles, you loose a ton of heat when nature drags you out of the bag in the middle of the night. When it's really going to be a cold or wet night, I take a pee bottle to bed. Sorry ladies, but this technique is discriminatory - definitely easier for the guys. I won't go into any more details, but find a Gatorade bottle (that can never be mistaken for a Nalgene drinking bottle) very useful. Takes some getting used to, but worth it!


Here's to toasty toes!



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This has been a very good thread. It also made me realize why my Mountain Hardware 2nd Dimesion bag doesn't keep as warm as I thought it would. I sleep on a cot, 18 inches off the ground, with a thermarest on the cot underneath my sleeping bag. I guess being up in the air is causing me to lose some of the heat and that is why I get chilly at a temp that I wouldn't expect based on the bag's warmth rating. A fleece throw over the bag does wonders as long as you don't toss and turn, but a flannel sheet inside the bag makes it nice and toasty.

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This is a great thread, very informative. Thanks everyone for you contributions! I have a related question - do you recommend any different tactics for small, skinny younger boys? We've got a bunch of 10-11 yos who are just all bones, hardly any body fat to speak of. Seems no matter what they try they're cold - and it is common for temps to get into single digits or low teens around here for 3-4 campouts each year. My son's one of these guys so any advice would certainly be welcome.


Also what's the view on those chemical hand/foot warmer packets?



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