this post was submitted on 05 Sep 2024

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Confused about sleeping bag temperature ratings (lemmy.world)

submitted 2 months ago by [email protected] to c/camping

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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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[–] [email protected] 19 points 2 months ago* (last edited 2 months ago) (3 children)

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.

[–] [email protected] 10 points 2 months ago

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

[–] [email protected] 3 points 2 months ago (2 children)

I guess I'll have put something over or inside it for cold nights.

[–] [email protected] 8 points 2 months ago

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.

[–] [email protected] 3 points 2 months ago* (last edited 2 months ago) (1 children)

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.

[–] [email protected] 2 points 2 months ago

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.

[–] [email protected] 2 points 2 months ago

Unless its a western mountaineering bag!

[–] Noel_Skum 11 points 2 months ago (1 children)

I was incredibly confused until I worked out you’re talking Fahrenheit… all I can add is what someone else said: the extreme rating is not a position you want to ever be in. Although it is preferable to death…

[–] [email protected] 1 points 2 months ago (1 children)

Sorry, I don't often think in metric.

[–] Noel_Skum 4 points 2 months ago

No apologies needed. It seems that I don’t often think in Fahrenheit…

[–] [email protected] 6 points 2 months ago (2 children)

Get a 0⁰ up to -20⁰ sleeping pad so the ground isn't sapping heat from you, wear warm clothes inside of it, and be ready to do some situps in the middle of the night to trap some heat in there, and you should be good. Personally, if I am going to be camping at any temp below freezing, I'll go for a zero or -20 bag since I have one, but a good sleeping pad and fleece base layers add a lot of protection whatever bag you're in.

[–] [email protected] 4 points 2 months ago (1 children)

From my experience I would say don't wear warm clothes in your sleeping bag. Just wear a light pair of thermal underwear (top and bottom) and some socks. Put your clothes into the bag with you to keep them warm but don't wear them. That way when you wake up and put on those clothes you actually feel warm. If you wear clothes in your sleeping bag you'll feel cold after you get out of your sleeping bag.

[–] [email protected] 1 points 2 months ago

Sure, if you have a sleeping bag that's warm enough. If you need the layers to sleep, you just gotta cope with a cold morning and get moving as quick as you can to heat up. Just saw that OP is car camping, but stuffing a tent, sleeping bag, and pad first thing every morning is always enough to get me warmed up in whatever layers I have on, if I am moving camp.

[–] [email protected] 1 points 2 months ago (1 children)

I car camp. I have a 6" foam pad.

[–] [email protected] 2 points 2 months ago (1 children)

That should help with the ground. I guess my advice would be to get out there and try it once before it's your coldest season. See if you're comfy at 40⁰ and then take your best guess about another 8⁰

[–] [email protected] 2 points 2 months ago (1 children)

Sounds like a plan. I'm currently at 7000 feet so I'm about to find out.

[–] [email protected] 1 points 2 months ago

Good luck!

[–] [email protected] 3 points 2 months ago (1 children)

Possibly. Who makes the bag? For the most part only the higher end bags actually have accurate ratings.

[–] [email protected] 1 points 2 months ago (1 children)

Grand Teton

[–] [email protected] 2 points 2 months ago* (last edited 2 months ago) (1 children)

Grand Teton

I'm not familiar with that brand and can't find any useful info about them. I'd recommend not trusting the rating on there until you've established performance for yourself, and to bring something warm to put on so if it doesn't live up to the rating you won't be too miserable.

Also, insulation from the ground is super important. If you don't have a good sleeping pad, that will make a huge difference.

[–] [email protected] 1 points 2 months ago (1 children)

Well it was $79 and made in China sooo, you know

[–] [email protected] 2 points 2 months ago

In that case, I wouldn't trust anything on the label or any of the packaging. If you can swing it, a quality down bag costs more up front but can last decades if you take proper care of it (mainly always store it dry and uncompressed, and avoid folding it). If you're just car camping it's maybe harder to justify but if you backpack at all the weight savings that come with down are really worth it. One of mine is almost 20 years old and still going strong, amortized over the life of the bag it was a great deal back when I bought it.

[–] [email protected] 1 points 2 months ago (1 children)

I would reckon that should work, if you are camping at those temperatures surely you must also have some dry layers to put on in your car if it gets too cold somehow. I was sleeping comfortable in my 25°F limit bag in a 32°F, non windy night (comfort temp 35°F) in just underpants. I am a hot sleeper though. If it is just the odd night i would noit worry, but i am also always keen to save weight and volume.

If you are scratching around the 32°F for multiple nights though, maybe look at some sleeping bag liners too, they're pretty cool and can be used nicely as a sole "bag" in summer and give you a few degrees extra in cold nights. Also way easier to wash than a sleeping bag.

And yeah, insulated pad is important, but seems like you are good on that end.

[–] [email protected] 2 points 2 months ago (1 children)

I've been looking at liners. Not only could they add a little bit of insulation but they're easy to just throw in the washing machine and your bag stays nice and clean.

[–] [email protected] 2 points 2 months ago (1 children)

I should maybe add that i have quite some experience camping, know what makes a good spot and how to set up my tent properly and will always have some more dry layers to put on if it gets too cold. I have quality sleeping bags, which temperature ratings i trust, or actually can confirm.

[–] [email protected] 2 points 2 months ago

It's good to always be prepared especially with a chance of bad weather.

[–] [email protected] -2 points 2 months ago

Where are you - Death Valley?