I live in far west Texas and backpack in NM but mostly in the Southern NM mountains which vary from about 7,000 to 11,000ft. Lincoln NF & Gila NF. I have been using a synthetic 5+lb sleeping bag that has kept me warm to the high teens and lower if I slept in my jacket in the Guadalupe mtns but never trusted it go any where else since Im unsure how much colder it gets compared to the nearest local town. Anyhow I have been looking for good quality sleeping bag to use in winter but not sure If a 0* bag would be over kill or if I should just get a 15* bag.
I've been checking the weather history for a local town in the Lincoln NF and it averages about lower 30* to upper twenties for night time temp in the winter with random monthly lows in the the single digits. Town is at about 7000ft. Since my current bag keeps me warm to about the high twenties(with just base layers) not sure if I should just take the plunge and get the 0* to get a good degree difference between bags or just get the 15* which is only about a bit more then 15 degrees warmer then my current setup.
Sleeping bag ratings are generally only a guideline - if you know you do well in the cool with baselayers on, then you may want to try the lighter weight bag. (I tend to be this way, and so I can often hit 5 degrees or so below bag rating before I start to want more bag) but everyone is a little different in this regard.
Do remember as well, that a lighter bag is not necessarily "lighter" overall if you have to carry 3 pounds of fleece in order to sleep comfortably in it - you might be lighter (although not necessarily more comfy) in the heavier bag with less stuff on - it really depends on you.
I do most of my hiking with a 28F and a 15F bag. (-3C and -10C). I go into deathly cold temperatures (-25 to 30C) by adding another syntheic bag overtop of my -10C bag. I don't own a "fancy" bag for serious cold.
What I have found is that most of the temperature ratings are at the very least very optimistic. I think ( I don't do this much) that if you were to purchase a "0" degree bag, it would probably be more like a "20" degree bag in reality. I do think that the better bag that you buy the temp ratings are a little closer as stated than the lesser expensive bags. Also I do think that if you buy down versus synthetic your temp ratings are generally a little closer... Hope that helps, but in reality they are only opinions...sabre11004
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I have no idea how manufacturers rate bags. There is a European testing protocol for bags sold in the EU. Here is how one manufacturer (MacPac) rates one of their bags using the EU test- "Temperature rating: Comfort -4˚C / Limit -11˚C / Extreme -30˚C"
What this shows is that ratings, even after standardized testing are subjective up to a point. I have a bag made by this company that is rated to -5C (+23F), which I think is pretty accurate for me. I have used it in colder temps down to about +15F (according to someone who told me that's how cold it had been the night before), but I was wearing my base layer and had my huge down parka (the one in my picture) on top of the bag as well.
If I was going to buy another bag for colder weather, I think I'd go for a big differential like a 0 degree bag. 5 or so degrees can be compensated for with more clothes or throwing a parka on top.
Edited by TomD (10/18/0909:10 PM)
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