Wisconsin here. Ranging from normal days around 20F to a few days around 0F. Coldest of the year is usually -10F. Coldest I’ve gone shooting was a beautiful ice-crystal encrusted sunny day at -25F, and a windy day at -20F.
Jackets: LL Bean Baxter State Parka. It’s too warm unless it’s <10F, but I’ve had it down to -20F and it’s cozy. Otherwise a bog standard Columbia jacket. I generally wear a sherpa-lined flannel underneath my coats, because layers are less sweaty and two layers and zippers make it easy to regulate temperature.
Hats: The parka hood is amazing at -20F and windy. I’ll use a floppy-eared fur-lined hat if it’s really cold or windy and I’m not using the parka. Knit cap if it’s just cool out (20F+). I have a face mask or scarf I’ll use if I need to keep my mouth warm, but in those cases I’m usually using the parka.
Gloves: Heat Company mitten shell (with flip-out fingers) with thin wool gloves underneath if it’s ~0F. Ski gloves work well with my Z9’s controls down to 10F. My GFX100S isn’t so easy to feel out, so I have to use a ski glove on my left hand and a thin glove on my right, and I keep my right hand in a pocket with a heat pack as much as possible. If it’s only cool, I use my normal winter gloves I got cheap from Costco.
Pants: Jeans down to 20F. Jeans with wool long underwear down to 10F. Snow pants below 10F, or if I’m going to be getting wet.
Boots: Some LL Bean hiking boots if there’s no deep snow and it’s >10F. Tall Muck Boots if it’s colder, or I’ll be in snow deeper than ankle depth. Wool socks, with or without ankle-high athletic socks underneath depending on temperature.
Heat packs: The standard soft pouches, sometimes stuffed into the back of my gloves. I also have a USB battery that has a heating function, and I will stick that in my right hand jacket pocket for extra warmth when I use a lighter glove for shooting.