Feathered Friends - Swallow UL 20/30

Female cold sleeper here with about 25 years of trying various sleep systems. I know you're only asking about a bag, but there are some other things she can also try to be more comfortable: * both WM and FF make great bags, and they'll be pretty accurate in terms of temp ratings. I bought a FF Swallow 20F in 2002 or so, and it's still in amazing shape. If it weren't so heavy (35oz, sob), I'd still be using it for every trip. I found it comfortable down to 30F. I switched to a quilt because I'm a restless sleeper, but I still love that bag. * consider a different sleeping pad, even if she doesn't think the cold is coming from the ground. I started off with a Thermarest SI back in the day, then switched to an old variation of the xlite and consistently froze my ass off. I then went to a Nemo Tensor All-Season, which ostensibly has the same r-value (a pretty blunt instrument to begin with), but sleeps \*significantly\* warmer, at least for me. I'd also recommend rectangular over mummy; it's made a huge difference in my sleep quality and warmth, and I'm happy to take the minor weight penalty. * consider different/more sleep layers. You mentioned in a comment that she sleeps in a merino base layer plus a puffy, and honestly that just might not be enough. My usual is just merino bottoms (unless I'm somewhere like the arctic, where I'll add lightweight fleece bottoms), but on top I'll almost always wear merino, a midweight layer (Patagonia R1 or MH Airmesh), and a puffy. Alpha might be a good add, too, I just haven't splurged on it yet. Last year on the Colorado Trail I often went to sleep in my rain pants, too, just until I warmed up enough to strip off in the middle of the night--though honestly that was probably because I had a crappy EE "20F" quilt. For a merino top, I love the Black Diamond Solution hoody--the hood adds a little more head warmth (and keeps your hat in place) for very little added weight. There have been nights where I've worn every damn layer I have, including my gloves! * hot water bottle! a true game-changer if she hasn't tried it. The downside is the weight of a bottle that can hold hot water (nalgene, not smart water) and the extra fuel you need to heat it up. It sucks to be a cold sleeper, and there's definitely a trade-off between weight and comfort. On a shorter trip I'll sacrifice comfort (no extra layers, no hot water bottle, sleep in my gross rain pants), but if I'm out for a month or two, I don't want to be miserable every night.

I say this as someone who has bought a lot of sleeping bags. It’s better to spend the money on something premium upfront. I bought a $100 then a $200 then a $300 sleeping bag… and still kept freezing my ass off. I now have a feathered friends swallow, and have no complaints. If I had just invested that money upfront, it would have saved me lots. Consider WM, FF, or pHdesigns for your next purchase. You won’t regret it

192cm here. Long versions of Feathered Friends, Western Mountaineering, or Enlightened Equipment bags. For your temp range I use 20F EE quilt. For a tent, you can also get something longer. I use Tarptent Rainbow which leaves me with almost 30 cm to spare length wise.

I paid $1k for a -40 degree sleeping bag. Because the -20 degree sleeping bag I bought the year before wasn’t warm enough. Feathered Friends. They are $1,200k now. Alaska is cold in March.

Western Mountaineering, Feathered Friends or Marmot for bags. Enlightened Equipment, Hammock Gear or Katabatic for backpacking quilts. Not cheap but quality and comfortable.

There isn’t really an absolute best, but I like Katabatic for a quilt and western mountaineering or feathered friends for a bag. I prefer quilts down to around the low 20s, bags below that. Having a pocket in your quilt for a sleeping pad seems silly to me.

At those temps you don't want to be messing around with some (relatively) unknown brand. I would also go insane if I had to deal with some fiddly hood that let in drafts around my neck in the winter. As far as I'm concerned, in the winter you have two options -- feathered friends or western mountaineering.

For sleeping bags I do Feathered Friends. PHENOMENAL products. Carefully selected down feathers and they don’t have to kill the animals to get them. I’ve got 3 different Feathered Friends sleeping bags for different temperatures, including an ultra thick one that I’ve used alone sleeping in no-tent self-dug snow trenches in the middle of Yellowstone in January. The outer layer of the sleeping bags is synthetic, but the primary ingredient is natural feathers. I also have one of their down packable jackets, but it’s too hot, even in -20F. Last time I camped in deep snow for a week, alone, on cross country skis, pulling all my gear on a Fairbanks siglin pulk sled behind me, I found I didn’t need much during the day, because I was working so hard I was always hot. At night I would dig a trench, lay a tarp across the top, supported by my ski poles, and sleep in my FF down bag on top of a thermarest. I’d keep my boots in the bottom of the sleeping bag so they didn’t freeze overnight. Wool socks, wool long underwear, wool sweater, synthetic wind-and-snow protecting pants and jacket. Wool hat, neck gaiter, and gloves. Synthetic outer-layer for gloves to keep my fingers drier. Smartwool makes merino wool boxer briefs. You need less than you think. (Except calories, holy f— do you need a lot of those.)

Sea to Summit bags are excellent. Western Mountaineering makes bags that are a little higher quality than S2S, and more expensive. Feathered Friends is another excellent bag. Both of these brands are small American companies who focus on making the best products they can, price be damned. If you’re at all concerned with price the Sea to Summit Spark will work just fine. If the price doesn’t bother you, Western Mountaineering or Feathered Friends bags will keep you warm and happy for decades.

Western Mountaineering and Feathered Friends are the best out there.