As long as you're not in the wind, there are ways to stay warm below 0. Begin with staying dry - don't over dress on your walk in - I often carry a pair of fresh, dry socks and switch out once I'm on stand.
Merino wool long underwear, heavy wool shirt and pants, fur vest, insulated fleece bibs, a wool or heavy fleece jacket, and a beaver fur hat. Fur is the warmest, lightest material I've found. On my hands I usually wear a pair of glove liners under a pair of fleece gloves with leather fingers and keep handwarmers in my outside pockets. On my feet either Danner Pronghorns 1000 gram insulation or pac-type boots.
Since moving to Nebraska, don't see those temperatures as often as when I lived in Wisconsin or North Dakota - a lot of the reason for the move! Pray I never have to move back.