Confused about sleeping bag temperature ratings
Confused about sleeping bag temperature ratings
Where I live it rarely gets down to 32 degrees. I bought a bag that said 20 degrees. After reading the manual it said that was the extreme rating. Will this bag keep me warm at 32 degrees or not?
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The extreme rating keeps you alive, barely.
Any decent sleeping bag will also have another rating, often called "comfort". This rating should be low enough to cover the lowest temperature you're going to use it for, but only if you're male and the bag's size fits you well.
Women (on average) and people who are smaller will need an even lower temperature rating.
Also, the rating assumes you're using a very well-insulated sleeping mat underneath, the bag is new, and completely dry.
So factor in some safety margin.A bag with an extreme rating of 20 will definitely not be warm enough to sleep well at a temperature of 32.
I would like to share a story here of the first time I went backpacking.
I rented my equipment from my university's gym. I had checked the weather, and the low temperature for the weekend was supposed to be about 45F. For sleeping bags I had 2 options, one rated for 32F and 15F. After talking with the student employee behind the counter, we agreed that I didn't need the 15F. I also decided not take a sleeping pad, because I slept outside on the bare ground quite a few times and felt it was unnecessary. I didn't think k about insulation at all.
That weekend there was an "unexpected cold snap" and the night time temps dropped into the low 20s. I set up camp right next to a river, and I didn't stake my rainfly out properly.
Holy shit I thought I was going to die. I took every bit of fabric I had and stuffed it into my sleeping bag, but it still wasn't enough. All night, condensation collected on the fly and dripped onto my face. It was like Chinese water torture on top of hypothermia. I also failed to build a fire and I couldn't cook dinner (no firestarters, no gas, and it had rained for a week before I got there).
I was hungry, freezing, and wet. That was the most miserable night of my life. I had to bail. At 5am I left and went to the closest McDonald's and got some shitty coffee and it was amazing in contrast lol
10 years later and I still overpack clothes because I have a fear that the temp might to drop 20 degrees unexpectedly.
So to anybody reading this and wondering about what bag to get. Go lower than you think you need (you can always sleep on top of it). Use a sleeping pad with good insulation (you can choose not to use it if its too hot). Don't set up camp right next to a body of water if you're not ready to deal with extra humidity. And learn how to properly use all your equipment before you set out. A properly staked out rainfly can make the difference between a good night's sleep and extreme psychological torture.
I swear I can still feel the drip drip drip on my face from that night haha
I guess I'll have put something over or inside it for cold nights.
You can absolutely be comfortable with extra blankets stuffed inside the bag. I have done exactly this using a bag with the exact same ratings. It was juuuuust below freezing all weekend, my bag was rated for 20 degrees, and I was cozy with a few extra fleece blankets cocooned inside the bag. Maybe bring a wool blanket or two if you’re expecting it to be wet at all, because wool will retain heat even when wet.
Also, change your damned socks before bed. Lots of newbie campers make the mistake of going “I don’t wanna take my socks off and get my feet cold right before bed. I’ll change my socks when I wake up!” In reality, if you go to bed with socks that have an entire day’s worth of sweat and skin oils soaked up, your feet will stay cold all night. Change into a fresh pair before bed, so they actually insulate your feet instead.
Get a sleeping bag liner. A flannel one will cost about $30 and boost the warmth of your sleeping bag considerably IF you need it.
Pro tip: If you are cold in your bag when you shouldn’t be it probably means you got too hot, started sweating, and now your cold because of evaporation. It took me YEARS to figure that out. I now leave my bag unzipped half way down so I don’t build up moisture inside and that keeps me from getting cold. I’ve comfortably slept in my bag many time in air temperature well below freezing since figuring that out.
Yes, I'm looking into sleeping bag liners to see what I like. But, I didn't know about the unzipping of the zipper. Thank you for the tip.
Unless its a western mountaineering bag!