In the American Northeast, winter hiking is not very popular. Winter walking, and cross-country skiing are popular, but 6 hour hikes are not. It's not so much the cold as it is because snow and ice do not make good footing for slopes, especially steep ones.
Still, I had a friend who hiked/climbed Mt. Washington in January because it was the most macho thing to do that he could think of. Kudos to him, because I do not think I could do that. Wish I could. (He had also enjoyed clearing tunnels and caves of Viet Cong back in the day, so he is a different sort of person.)
A few tips for cold weather (below 15 F) long (over 4 hr) hikes: Cold-Weather Hiking Tips