List your winter layers.

I’m trying to figure out the “science” of layering and what gear to buy. No one has ever taught me, and can confirm that wearing a puffy as your second layer under a rain jacket on the approach to buttermilk falls is a terrible idea. Since that experience I’ve gained an understanding of how to layer, but trying to sort through the million merchandise choices is challenging, and some other mp posts discussing the topic get rather long winded.

My request is, would you mind making a brief list of all your winter layers from inner to outmost and the general conditions you climb in. Please and thanks. 

Tshirt/Sunshirt > 2x Fleece (dependent on how cold its going get) > Softshell or Windshell > Huge Puffy (For chillen purpose xd) ... I never carry a hardshell unless I am alpine climbing or backpacking 

Ice climbing:

Top: wool t-shirt or long sleeve (smart wool or icebreaker), synthetic layer (Himali Ascent Hoodie), down belay parka while stationary (North Face L5)

Bottom: wool long underwear (icebreaker 200 oasis), thick soft shell pants (OR cirque II), wool socks depending on your boots 

Pro tip: bring a separate pair of socks/ shirt to change into at the base of your intended climb if there is a long approach 

mountaineering/ ski mountaineering:

Top: wool t-shirt, active synthetic layer (something that breathes well with high activity) (melanzana hoodie, OR ascendant, etc), then softshell (OR ferossi hoodie)

Bottom: wool long underwear if appropriate, softshell pants (OR Cirque II, OR trail breakers, or similar), wool socks dependent on boots

rock climbing:

Top: t-shirt preferably wool or sun hoody, softshell (thicker: OR Ferrosi, thinner: OR astroman), synthetic jacket for belaying sometimes (rab xenon, Patagonia nano puff, etc.)

Bottom: softshell pants of varying thickness (OR Ferrosi pants, Eddie Bauer guide pants etc.)

Thin zip-neck tee, Patagonia R1 Hoody, shell. Light puffy if needed. DAS parka if really cold. Add a beanie and/ or balaclava if cold. 

Light or medium synthetic long underwear, soft shell pants. Usually carry two pairs of gloves, more if ice climbing, or add a pair of mittens. 

winter mountainerring in the alps/ice climbing/ski touring:
top:
Medium weight merino wool termal top, long sleeves
Patagonia R1 hoody
Lightweight sofshell
in the bag: lightweight hardshell and heavy weight down jacket
Bottom:
Merino wool brief
3/4 merino longjohns
Softshell pants
Acessories:
wool buff
Arteryx wool toque
merino wool socks medium thickness, not the super high one, just above the boots is enough

I almost never wear hardshell pants, the one I own is gortex paclite.

TL DR: base layers change with temps, midlayers should breathe (grid fleeces and active midlayers) and everyone is climbing in softshells top and bottom basically always, with a belay puffy. 

Base layer, R1, atom Lt, alpha hybrid shell on top. I tend to hike in the r1, climb in the LT and shell, but sometimes put the atom in the pack. I have a big belay puffy, and my pants are softshells that I would wear one or two light pairs of long underwear under. I did tons of NE ice with these layers, mostly moving the shell top and atom into and out of the pack depending on exertion.

1. Fishnet Baselayer (Brynje or Castelli Miracolo)
2. lightweight Polartec Alpha Direct  hoody
3. Polartec Neoshell hardshell or OR Windshirt

Notes:

• mid layer (2) is often not necessary, if weather is mild or effort is high.
• sometimes leave baselayer 1 off and wear Alpha Direct (2) next to skin, if I suspect that all 3 will be to warm, but just fishnet will be too cold.
• For the shells, need to have something  VERY breathable: Gore Shakedry, Super thin Gore Active, Neoshell, Ascentshell, thin Futurelight. Same for windshells.
• For the shells, venting is essential: longfront zipper,  cuff that open, sleeves that  push up, pitzips/side zips.

The reason for this system is as follows:

First of all, it has been lab and field tested to provide the best breathability and quick drying across a wide range of conditions. It allows you to sense moisture immediately, so you can adjust before you get wet.If you do get wet, it dries very fast, and the layers never feel wet and clammy,

Second, it is simple.

Third:

On a typical outing, conditions are variable. In the past, I struggled to adjust for that quickly. When you think about it, air temp does not change rapidly. sun and wind are what changes quickly and often, due to shelter or not, or clouds.

So, instead of changing the insulation level, I keep that the same, and adjust by opening or closing shells venting. This is also the only way to dump lots of moisture if you are working hard.

The fishnet and PT Alpha Direct are both so open weave, that as soon as you expose them to the outside air, you have almost no warmth left.

This can be done even while wearing a harness and backpack, which is the biggest advantage over adding/subtracting layers.

This system works from windchills just above 32F/0C down to windchills around -32F/C. I have the Neoshell, because I need a custom size. If you can fit in standard sizes, and can get a Gore Shakedry shell jacket, it will go down to even lower temps, because Goretex is non air permeable, while Neoshell is, so you lose some ‘range’ at the colder, windier end of the scale.

The above is for ‘active use’. Then layer high loft insulation like down or Primaloft over the top as needed for rest, belaying, skiing downhill, slow movement in extreme cold, etc. In rare conditions (cold, wet rest) layer high loft insulation under the hardshell.

I see you're in the Northeast, so here's what I wore when hiking the Winter 115 (NH 48, ADK 46, etc...)

• Bottoms
  • Thermal bottoms - different weight depending on conditions
  • Mammut Champ Pants (No longer sold, but I found the BD Dawn Patrol ski pants are a pretty close alternative, but have a ton of ski specific features)
• Tops
  • Thermal top (minus 33 merino midweight, or a long sleeve merino tee)
  • (Condition Dependent) - A lightweight full-zip hooded fleece layer (think R1 or similar)
  • Mammut Ultimate Hoody (Light/midweight Windstopper Softshell) - Good enough to stop the wind and shed snow for schwacking through trees. Generally too hot for below treeline high-output activities, but it vents really well
  • Lightweight puffy for the descent (Micro Puff, MHW Compressor, etc...) - Spends most of its time in the pack
    • On really cold days, I'd replace this with a lightweight down puffy
  • Ultralight Wind Shirt - This is the most versatile piece of kit, since you can add it at any stage in your layering to add a few more degrees of warmth 
• In the pack
  • Hardshell (MHW Dry Q Elite shell, can't remember the name, but best breathing hard shell I've ever owned) and full zip hardshell pants (I actually usually carried full zip summer rain pants since they were used so infrequently, and really I just needed them for the windproof nature on nasty days above treeline)
  • Emergency Puffy - Rab Neutrino Endurance

This combo got me from temps from +40 down to negative single digits

For backcountry skiing, same scheme with thermals, but different softshell layers

• Top
  • OR Ascendant (Polartec Alpha) - Would consider a nano air from patagonia as a replacement
• Bottom
  • BD Dawn Patrol Pants - Have vents which are really nice on the climb
• In Pack
  • Wind Shirt
  • Rab heavy/insulated soft shell for the descent
  • Emergency Puffy

This layering setup works in the 20s down to upper single digits (it gets a bit iffy below +10). On colder days, I'll add a puffy vest between the thermals and the ascendant.

For Rainier, I used the NE layering kit, but with the ascendant, but Nicole used her Ultimate Hoody - I found her layering choice to be the better option since we were going "low and slow" and I would've liked the extra wind resistance since it was windy the whole time. Overall I've found the active insulation pieces to be kinda niche and I'm not totally in love with them (but I keep buying (used) gear to try out different combinations).

The one most important thing to figure out is how to expand the comfort range of any of your layering systems so that you're not constantly stopping and adjusting.

• Maximum Warmth
  • Everything fully zipped up
  • Cinched hood and jacket wrists
  • All vents closed
• Moderate Activity
  • Hood off
  • Wrists un-cinched
  • Vents open
• I'm getting too hot, but I don't want to layer down yet (a dangerous game if you wet out all your layers...)
  • Fully opened front zipper
  • Roll up pant legs (if that works) and sleeves

One day driving to the trailhead, we were thinking about how much it would cost to go in and buy our normal hiking kit at MSRP and realized that we were walking around with like $1200 on our bodies/packs (in clothing alone). Remember that MP for sale, classifieds, consignment shops (and even Poshmark) are your friend for getting good deals and experimenting with different layering strategies. 

If you run hot and wet get Tjaard's kit. It's what dreams are made of. I use Patagonia air capilene hoody and it's probably warmer than mesh, and while it breathes and wicks better than anything else I have it doesn't breathe and wick like mesh. My midlayer is also polartech alpha with quantum air facing, but again this won't breathe as well as alpha direct because of the facing. If I don't need a shell I won't wear one, but often I need an additional shell for wind or precip or wet ice. I am then stuffier than desired.

On my legs I try to use full or 3\4 zip pants to vent as much as possible on the approach. I also have 3\4 length full zip tights I can add after the approach without taking boots off. Company is Northern Playground. 

Good info above. I'll just add that for the northeast specifically, hardshell layers are extremely useful still for cutting wind and wet ice. They are probably the most effective warmth per weight above treeline.

If you're in the whites / Maine on colder days, the many available Denali winter layer lists are good references as conditions are similar.