bowhunting at -20F I can sit for 4-6 hours or at -30F for 2 hours. Colder than that the deer get a pass. My setup is the following:
Muck Arctic Sport supplemented with chemical heat pack under the toes
Pair of tight fitting nitrile gloves (tight dish gloves will do in a pinch) worn inside thick thinsulate mitts. When a deer comes in pull the mitts off and you can still draw the bow with the gloves on. The under gloves give you precious extra minutes to hold your draw. I have magnets sewn into the mitts and my jacket so I can attach the mitt to my jacket when I pull it off. This prevents it from falling out of the stand.
- Bass Pro Lifetime Hunting Socks
- thermal long johns and top (polypropylene)
- light fleece top and and pants
- heavy fleece top and pants (Alternatively if really cold I use heavy cowichan wool or worst case both wool and fleece or sometimes a down bomber)
- Wind proof pants and jacket ( I use gore-tex pro shell)
- Fleece balaclava that seals down around the neck inside the heavy fleece top
- Beaver fur hat on top of balaclava
Add about 15 minutes to your routine as it takes about this long to put all this on. Layers are important as you can walk out in minimal gear so you don't work up a sweat and than gear up right before you go up the tree. Also I do not spray any scent control product on the clothes as this makes them damp and will cause a chill. If you really want scent control product spray the clothes several hours before so they can dry.
Also if your teeth start to chatter and you can't stop them than it's time to go no matter how long you have been out. If it gets to this stage be extra careful getting out of the stand as your coordination may be comprised.
Also no cotton whatsoever (not even a t-shirt or underwear). When and if you sweat the cotton will stay wet and act like a heat sink and suck the heat out of your body.
Check out the following:http://www.sitkagear.com
They make good stuff but it is pricey.