I'm looking to climb Aconcagua in a few years and I saw that most people recommend a -10° to -20° bag. I know that I'm a cold sleeper so I was leaning toward the -20° but I also don't see any reason to have two expedition weight bags. I was wondering if I could just get a -40° bag and take it with me to other places like Denali or Vinson, or would I sweat do death?

neither a -20 or -40 is necessary. A zero is adequate assuming you have a reasonably efficient and dialed sleep system. You have puffy pants and a big parka that you will sleep in on the upper mountain and the zero will be plenty down low.

I completely agree. I also added a thin liner to my bag (0 deg. rating) and climbed in with my down pants and parka at high camp.

With all the gear/supplies I carried, taking a burlier bag than necessary would have been an added hassle (and uncomfortable lower down as stated above).

Woodie

The extra weight and bulk of a -40 bag will be unwelcome on a high altitude climb. A huge bag is a pain to stuff and cinch down to the point where it doesn't take up an unwelcome amount of your pack capacity. I wouldn't go any heavier than -20, and the current best practice (as mentioned above) is to take an even lighter bag and wear your down clothing in it. I have had the privilege of meeting some climbers who have ascended multiple 8000 meter peaks and they told me the same thing. On those mountains, they sleep in their down suit in a lighter bag at the high camps. Those down suits already weigh 4+ lbs, why carry another 4+ lb?

Thanks for the help everyone, but I guess that brings up another question. I had also read that you don't need down pants for Aconcagua, just a good baselayer softshell and hard shell. Is this true?

Puffy pants are optional. Just really really nice to have.

Medium weight softshell pants, medium weight long underwear, and light weight hard shell pants will generally be enough for your lower body.

Would you put your puffy pants under or over your gore tex layer?

Edmund wrote:I'm looking to climb Aconcagua in a few years and I saw that most people recommend a -10° to -20° bag. I know that I'm a cold sleeper so I was leaning toward the -20° but I also don't see any reason to have two expedition weight bags. I was wondering if I could just get a -40° bag and take it with me to other places like Denali or Vinson, or would I sweat do death?

I just bought a new sleeping bag for Acon, Vinson, Denali etc and wanna use the same bag for all of them. I do prefer sleeping with less clothing and preferable only in underwear. To avoid getting to warm I have a lightweight sleeping bag liner with me, so if its to warm I will just sleep in the liner with the sleeping bag as a quilt on top.

I don't have much use for a -20/-40 bag if I need one I'll rent it.

I've been in Norwegian mountains and based from my experience, if it;s rated to -20 C. (-4 F.) go for lightweight. The lighter down bags also are the most compact. A great example is the Lynx MF from Western Mountaineering. Having anything bulk wouldn't be your best choice as there are many options you can thermal yourself.


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I was on Aconcagua in 2014 late in season (and plan to go back this year), so a little colder than you'll probably see. The down pants might not be essential but they sure are nice at high camp and if you go for the 0 degree bag, and I think they're worth it. The -20 bag I took was too warm the whole trip. I sleep cold too.

For Vinson and Denali I don't think you need a -40. My friend just summited Denali with a -20 and he said it was no trouble. If you get cold you just put more jackets on.

In short, I have a -20 and intend to all three peaks and Everest in 2018 with it.

Edmund wrote:I'm looking to climb Aconcagua in a few years and I saw that most people recommend a -10° to -20° bag. I know that I'm a cold sleeper so I was leaning toward the -20° but I also don't see any reason to have two expedition weight bags. I was wondering if I could just get a -40° bag and take it with me to other places like Denali or Vinson, or would I sweat do death?

I sleep cold too so I'd suggest you go with the -20 bag. It will probably only weight 1 lb more than a 0 degree bag. Buy a good stuff sack with compression straps and even a -40 degree down bag can be smashed down pretty small. I hate sleeping in my 0 bag while wearing multiple bulky layers. Almost impossible to get any sleep with the lack of movement from wearing puffys combined with altitude insomnia. I'm headed to Andes in a few days to summit a peak over 6500 meters and I'm bringing the big gun, my -40 degree marmot CWM with a rab stuff sack fitted with 4 compression straps or maximal compression. It's a trade off, more weight and bulk for better more comfortable sleep. I'll take the sleep.

I used a Marmot Couloir "0" bag on Aconcagua in January 2007. At various times during the three week expedition our team experienced ambient night time temps ranging from around +10 down to -20F. I was always quite comfortable in my 0 bag. On particularly cold nights, I would wear expedition weight long underwear. Some members of our climbing team used -20 and -40 bags and a few used 0 bags.

Your choice of bag basically comes down to two things; 1) Your own personal comfort level. Some people just need a very warm bag and 2) The quality of your bag. Not all 0 bags are created equal. You get what you pay for.

In any case, I would not worry about weight difference among bags. If you need a -40 bag, get one! Better to carry a few extra ounces than compromise your climb.