I'm not sure how cold it got last night, but when I got up at 6:30am and came in, the Intarweb told me it was 20 degrees fahrenheit, and what data I could find retroactively seemed to point to a low in the mid-teens (I didn't think to look at the forecast before going to bed).
Let me put it this way: There was ice on the inside of the tent walls this morning, presumably from breath vapor condensation. But I slept very warmly in my DuoFold® Union Suit and Coleman® mummy bag, under a World War II wool military blanket. Matter of fact, I removed the blanket during the night. I did, however, use an old t-shirt as a sort of "veil" to loosely cover the part of my face the mummy hood leaves exposed (a cold nose is annoying).
I'm still not sure what exact model that mummy bag is (I found it at a thrift store) but I'm still guessing it's either an older model of, or equivalent to, the Coleman® Everglades 20 degree bag. It's definitely a Coleman®. It's 85-inches in length with a built-in stuff sack, and contains 3 pounds, 10 ounces of DuPont® Holofill® insulation, both of which match older "Everglades" descriptions (Coleman® has switched to its own "Coletherm®" insulation recently, and new "Everglades" models say they're good down to 10 degrees instead of 20).
I can't recommend it enough. It's a fine bag. So hey, I might as well do a "mini-review" for those who are considering cold-weather camping.
First warning: Mummy bags are not for the claustrophobic. Getting into and out of one properly takes some time, and when you're in them you are essentially immobilized.
Here's how you get into the bag -- Or how I do, anyway:
- First, lay out and arrange the bag pretty much exactly how you want it to be positioned for the night. For instance, if you are using pillows, make sure the bottom of the hood area is up on the pillow. As we shall see, changing position is not the easiest thing once you're in the bag.
- Next, get in the bag (which obviously must be at least mostly unzipped for you to do), zip it halfway or so, then turn out any lights, etc. -- because in about 10 seconds you're not going to be able to reach out for stuff.
- Lie down on your back. Find the two drawstrings on your left -- one for the chest baffle, one for the hood -- and make sure you know where they are (I lay them across my chest at a downward angle).
- Finish zipping the bag, and attach the little velcro tab under the zipper handle that keeps accidental unzips from happening. One nice feature of this bag is that there's a cloth tube/baffle that lays over the zipper on the inside, protecting you from drafts or contact with cold zipper material.
- It's already a bit snug, but now let's address those drawstrings. First, close the chest baffle by attaching the velcro tabs on the right side. Then cinch up the drawstring for the hood until your head is completely enclosed except for your eyes, nose and mouth (and as little of those as you care to leave exposed -- if you want to veil your face with a piece of cloth in that space, now is the time). Finally, cinch up the chest baffle until it's tight around your shoulder/chest area.
You're done -- and within perhaps five minutes, you'll be comfortably warm. The bag does a great job of sealing in body heat, especially since that chest baffle doesn't let it escape up top.
I'm a fairly big guy, but not wildly obese or anything. When I'm fully in the bag, I have about 4 inches of space in any of three directions (left, right or up) before I'm pushing hard against the bag. If you want to change body position, it's going to take an effort and the bag is going to roll with you. Personally, I'm getting used to sleeping on my back. The immobility is actually a sort of sleep aid for me.
Like I said, don't try this if you're claustrophobic. But I guess if you were claustrophobic, you wouldn't be sleeping in a 7x7 foot, 4 foot high tent anyway, would you?
You don't want to wear a bunch of clothing in this bag. Not only does that further constrict your motion, but it's likely to get you sweaty and defeat the warming mechanism. Pajamas or long underwear, at the most, should be enough.
Getting out of the bag is just a reversal of process -- un-cinch the chest baffle and hood drawstrings, tear the chest baffle velcro loose, reach a finger out to remove the zipper-stop tab, and unzip. It takes a good five minutes to get into the bag properly; maybe a minute to get out, plus whatever time you spend delaying because man, it's cold out there.
At somewhere south of 20 degrees, I was toasty warm and comfortable all night -- so much so that I did a roll in the middle of the night to get the wool blanket off and cool things off a bit. But of course I was also wearing that merino wool Union Suit. I'm interested to see how I fare at full zero degrees. I'm certain that this bag isn't rated for that, but I expect to manage just fine.
Disclosure: Coleman® didn't pay me to write this. Coleman® didn't give me the bag, a discount on the bag, or anything like that. So far as I know, Coleman® doesn't know who I am (but I'll take any free stuff they want to send me!). They've been a reputable name in the camping gear business for decades, and that reputation is, so far as I can tell, well-deserved.