i want to get a sleeping bag that i can use in all conditions. (backpacking in the fall, car camping in summer, even going on trips and using htem in hotels, etc...)

if i get a 0 degree bag, would it be too warm for summer camping when nighttime temperatures are in the 40-50's?

yeah

A Zero-Farenheit bag? Oh my word yes. You will be miserable. Seriously. Sure, you can open up the bag and drape it over yourself as a quilt -- but -- anything covered by the bag will be sweating profusely, and anything uncovered will be cold.

Using a 0-F bag in a hotel would be even worse. Yikes. Sorry. You will sweat like the proverbial pig..

My personal recommendation would be a bag that you can use in cool weather -- say a good quality 30-F bag to start. Then if you end up wanting to hike in very cold weather, you can pick up the 0-F bag. Even then the 30-F bag has been far too warm for me in the summer.

If your original question was about a 0-C bag, then you should be fine.

I've never used a 0 degree bag (though I've camped at 0 degrees) but I think you'll be better off buying two bags of different ratings. You can consider buying ones that would fit inside each other, but if the loft is compressed it won't "count" as much. I have heard that the montbell superstretch bags (the lightest #7 one for example) work well as liners. I've never done this though. I use quilts myself, which can be easily layered if needed. If you're not familiar with quilts, check out jacksrbetter.com for examples.. I'm not carrying grandma's quilt!

Edit: I did a search for "combining bags" on backpackinglight's FORUMS and found a few articles you may want to read.

Two bags, get two bags. <img src="/forums/images/graemlins/crazy.gif" alt="" />

I think it depends on your personal body metabolism. I bascially have one bag, a 10-degree rated WM Super Antelope that weighs 2# 12 oz. I did not need all that warmth for 9 out of 10 nights on my recent trip. One night it got below freezing and I was glad to have it. My body seems to simply shut down on producing warmth when I sleep, so for me, it is not too warm. On warmer nights I drape it over me. Do not rely on the bag "ratings", rather consider your personal needs.

My personal rule-of-thumb is "no bag over 3 pounds". I could get a 35-degree "summer" bag but that would only save a few ounces, unless I were to spend lots of money to get the high quality lighter weight bag. With a limited budget, I need the money to pay for gas!

Overall, probably 50% of my nights out are below freezing. My "shoulder seasons" nights are usually around 15-20 degrees. If you hike in a warmer climate, then, a zero-degree bag may be too warm.

Perhaps I'm a cold sleeper--although I once did a bivy in the back of my car at 35F with nothing but my office clothes and some newspaper for insulation--but I've comfortably slept in down bags rated at 0F and below at nightime temps of 60F and above.

Back in the early '70s, we were teens and could only afford one bag that would have to do for both winters in the Sierra (once above 13,000 feet) and also summers in Joshua Tree. There were no temperature ratings then, but we all had bags with about three pounds of down and a loft of 7 inches or so--the equivalent of a modern 0 to 10 degree-rated bag. And you know what, we did just fine--I worked at a summer camp in the high desert of San Diego County, and for 70 straight nights slept in the same bag that I used for a winter climb of Whitney.

Down is much more breathable than synthetic insulation--in winter I sleep in my house in a Marmot OF bag, and in the summer (when temperatures can often be 85F at midnight) in a 30F Feathered Friends bag. I've tried the same thing with an ID Emperor (primaloft, rated at 0F) and there was plenty of sweat.

A Feathered Friends Snow Bunting, WM Super Antelope, or Marmot Lithium would all be relatively lightweight do all bags for 0F up to whatever you can stand.

There are a few things to try if the bag (down) is too warm for the warm night.

0) Open the bag into something like a quilt.

1) Use your boots to lift up the edges of the "quilt" and create air flow.

2) Have arms or legs outside the "quilt", and get them cooling you off. Same with head, maximum cooling of the head area.

These worked OK for me a long time ago, when I had only 5*F warm down mummy bag. For summer use, I eventually bought a very light Trailwise bag - that was a long time ago.

So, it is possible to get a bag too warm for summer. But there are some inexpensive light synthetic summer bags to tide you through the heat season.

Jim

1) Get bags with full length zippers so you can use them open like a blanket in warmer conditions. That might be 50 degrees for the summer bag solo, or 30 degrees for the winter bag solo. As others mentioned, consider two bags for the coldest conditions, so the outer bag needs to be roomy to keep from compressing the summer bag. By using the summer bag as a liner, you do not need a full 0 degree winter bag. Maybe a roomy 15 degree bag will suffice. Loft is insualtion, so whatever keeps you warm at 0 degrees now is near the needed loft of the two bags combined. Don't just lay them one on top of the other, check the fit with them combined, then measure the loft. I shop for top quality used bags on eBay and check there once a week, year round. There are categories for down or synthetic and temp. ratings (+15 to +30 is one) to help you sort the listings. For winter sleeping when wearing more clothes inside the combined bags, the summer liner bag may need a roomier fit than most summer-only bags.

I have two bags. One is my "beater bag." It is a Kelty Lightyear 25F (more like a 35 or 40 F) that I use for summer. I don't worry to much about it getting dirty and whatnot. My other is a WM Ultralight Super with overfill. That's my shoulder season bag. If I ever get into serious winter trips then I will pick up a zero degree bag. I doubt I would ever need one around here in Western PA.

It most certainly will be too warm. My first sleeping bag was a 0 degree quallofill bag, which was originally bought for shoulder season camping where min temps would be ~15-20C. I also used it when car camping on kayak trips during the spring/summer. I experienced the same min summer temps you expect, and sweated profusely throughout the night. Even when the bag was unzipped and used as a blanket I still was way too warm.

I though it was due to my metabolism (I am usually a warm sleeper), but when I got a new 3 season bag more closely matched to the temps I encountered, I didn't sweat nearly as much as I used to. In addition, I made myself a down quilt, for those 50C summer nights, which can also be thrown over my 25F bag to extend its range into the teens.

I used a Trailwise Slimline bag rated at zero degrees for years, for all conditions, and it worked fine, but was occasionally too warm. I get cold easily, so I was sometimes glad I had the extra warmth. A good quality down bag rated at about 20 degrees is probably as close as you'll get to an all-around bag.

What you're using for shelter makes a big difference. If you like to sleep out under the stars, you'll need a somewhat warmer bag than if you're in a tent.

Also, many budget-priced bags are rated very optimistically. Check the overall loft. To my way of thinking, a zero-degree bag will have about 7" of overall loft, and a 20-degree bag will have about 5.5" of loft. I'm talking only about mummy-type bags here, with a hood and draft flap.

Like :wumpscut: says...
"You will roast, you will burn"
"You're roasting!"