Big 2/3 for the lady

Not sure where you're planning to hike, but just for some comparison, I used a Western Mountaineering "Aspen" 25° and a silk liner last year on the JMT in September, and froze every night except maybe two nights. For reference, I was using a Large NeoAir with a Gossamer Gear "Thinlight" pad underneath. We were in a Six Moon Designs "Lunar Duo." I'm 5'7", regular build, my friend is 6', thin build (she used a 40° WM MityLite and silk liner and also froze.) I had on my Patagonia down sweater, and most of the rest of my clothes on every night (made for a very thin pillow.) The worst part was that I couldn't keep my feet warm–I was to the point of tears one night. It did snow on us the first couple of days, so it was pretty cold, but it was the last couple of nights that were the worst–around Dollar Lake and beyond.

So, if I were to do it again, I would bring a heavier sleeping bag, I should have taken my 15° WM "Ponderosa." The hiking was fine, it was sleeping that was the toughest. When you're cold, it's not easy to sleep. And it wasn't due to going to bed hungry. We took 1-1/2 lbs. of food per person, per day, this was too much food. All FBC style, just boil water for meals, soups, ramen, mac & cheese, etc. My favorite meal was when I had Cap'n Crunch and Nido milk for breakfast. Not sure why, but that was the best. I gave away so much candy and snacks to very happy hikers. I will do 1 lb. per person per day next time.

I'd get a big quilt to share from Jacks 'R Better. Shared bodily warmth never goes out of style.

Down booties for cooler temps. They make sleeping sublime.

Freezing all night after aching shoulders all day would be a bad introduction to backpacking, in my opinion.

I have two backpacking women in my life, a spouse and a daughter. Both require far more insulation than I do for the same temps, and both require a pack that transfers most or all of the weight to the hips. In addition, shoulder stabilizer straps ("load lifters") and a well-designed curved shoulder suspension are key elements in a comfortable pack.

My wife has two Montbell UL SS bags, a #0 and a #3, and she carries the #3 all summer. She's all zipped up when I am lying on my pad sweating. For a pack, she spent a couple of years trying on every light and UL pack on the market, and now she carries an Osprey Ariel 55. Yes, it's almost 4 pounds. Yes, I have implored her to try a Circuit, or an Ohm, or any other light framed pack that would shave pounds off her base weight. She tries them on, walks around the store, and then puts all her gear back in the Ariel. A frameless pack is a total non-starter.

My daughter uses an REI Sub-Kilo and an older REI Flash UL 45 pack. Her problem with packs has always been with the hip belt — she is so skinny that most hip belts met in the middle long before they were tight enough to transfer any weight. The Flash 45 works very well (not sure if the new one is different.)

Anyway, that's my experience. Yours will certainly vary. Good luck.

My first attempts at backpackin with the wife were… well, she doesn't think much of 3/8in foam pads anymore. She had never car camped, let alone carried everythingn she needed on her back. She ended up with a Osprey Aura, a Prolite Plus short, and a fleece liner for her bag (even in summer, I don't know how she stands it), and is all smiles now. I just carry all the shared gear (shelter, stove, etc) to keep her base weight down, and allow her full command of the kitchen (good for both of us). She also enjoyed the addition of some ergo cork trekking poles (she's a nurse, she can afford all of it! :P)

I guess what I'm saying is, I'd rather carry more weight, and maybe hike a little slower, then her have a negative experience. The more "spartan" trips and ounce counting can happen on trips with the guys.

I'd consider a warmer bag (or a liner), a frilly framed pack (I know, just let it go), and a couple of handwarmers that you can whip out when her feet get cold at night, and make yourself a hero ;-P

Good luck!

My wife has finally started backpacking with me and she uses a Marmot 20deg bag. She is usually zipped up all the way when I have my quilt half on me. She also could find a ul backpack that she liked. It ended up between a Granite Gear Zapor KI and a Deuter ACT Lite 45+10. And she also will not go without her Neoair.

And good call on the down booties. I should order some for her.

+1 on the Deuter ACT Lite packs. They're not terribly heavy and at least for mine I have nearly complete transfer of weight to my hips. I love my pack. LOVE. No pinch points and no soreness in front of my shoulders where in other packs my arms would hit against the straps all day.

I also have Montbell SS bags…a #0 and #3. I really wouldn't want to use the #0 at anything below freezing, maybe 25….seriously. And I just tried my #3 for the first time this past weekend, lowest temp 60. I was fine but I can see where I would not be happy at much below 45 with it.

Down booties, down sweater…YES. I'll be getting them come fall. Make sure she has a hat and gloves.

Exped air pillow. 3oz for heaven.

And get a chair to go with her pad. I've learned that if my rear end ever gets cold from sitting on the ground I will NEVER get warmed up again.

Because of the above items, I will never be truly UL. But I don't care. I am comfy and happy.

Thanks very much for the thoughtful responses. You're right, I'm trying to mold her wants from mine. I guess we'll have to try some things, and I'll definitely be more focused on her warmth!

Sorry. Not that anybody was sitting on the edge of their seat, but we choose the Deuter. She also loves how it transfers the weight to the hips.

I tried on a lot of packs and the Osprey Hornet felt best to me.
WM Caribou because I'm always cold and sleep restlessly, with MB Down Inner Jacket and pants if really cold
Smart wool top and bottom to sleep in
Windshirt made a huge difference
Kooka Bay sleeping pad with a short piece of foam on top
Hike in Arcteryx pants (can rollup to knees if warm). TNF has similar but heavier
If in desert and thorny use Railriders Adventure pants
Top Railriders long sleeve with the ventilated sides
I have rain pants/jacket but have only used as extra warmth so far

I've tried lots of stuff to figure out what I like. Your girlfriend will need probably need to do the same- hope she finds it as much fun as me

Two person quilt/bag! There are plenty of ways to ensure her warmth, but few that are as weight efficient as her having a giant hot water bottle that walks itself to the campsite! Plus if she's only used to car camping she might not sleep soundly at first out in the wilderness and having the reassuring and familiar cuddling of a significant other may help with this.

Spend a lot of time researching sleeping pads. Most people get cold from inadequate pad insulation…not necessarily just cold bags. Neo Airs, while comfy, bleed heat like a block of dry ice. You'll notice that often the "women's" versions of sleeping pads tend to be heavier and have higher R-value rating.

I would say get a down-mat. Expeds are probably overkill but may be worth the weight. A Kookabay custom should be considerably lighter, but not as warm in arctic conditions.

Often cold feet is a circulation problem…ie too tight socks. Down booties provide the insulation and shouldn't constrict blood flow.

Framed packs designed for women are, well, designed for women. Most UL packs are tested with men. The weight to hips transfer is a huge matter of importance for women. Honestly, whatever fits your body comfortably (male of female) will always be the best pack, regardless of it's weight. Comfort first, weight second when it comes to the pack.

In the beginning assume that she will feel 20-30F colder than you will and pack accordingly…you can lighten from there. You don't want her miserable the first time out, slowly ease her into the pursuit. Once she's comfortable she can then start playing with systems and trying to maximize fun while minimizing weight. From a cost perspective

-Dustin