I completed the Adirondack 46 this fall and have hiked them in all seasons. Winter hiking in the high peak region of the Northeast is no joke and you need to plan for weather conditions to turn on a dime. I did one hike in which temps were in the -20-30 range with wind chills in the -40 to -50 range, and my water completely froze halfway up. Mind you everything was insulated. The trail was also unbroken after a decent size snowfall so every step was breaking new trail, it was absolutely brutal. I wanted to turn around a few times but kept trekking through it. 3/4 of the way through the hike it started snowing heavily and whiteout conditions hit out of no where. The weather forecast did not hint at snow like what fell. It was a 20 mile hike and it was the only one out of the 46 where I felt like I shouldn't have been there. I have completed over 15 hikes in the winter up there. I did one hike solo in the winter, but would never recommend going up on these high peaks without a partner. I've seen so many people unprepared for these hikes in all the seasons. You need to watch countless videos on youtube to learn what to bring, how to plan out your trip, and back up options incase your GPS has issues. With temps in that range your phone battery dies so fast, people that use alltrails or other apps can have no navigation if their phone goes down. Here is a picture from that hike about half way up.
I've hiked some 10k+ peaks in the west and the northeast hikes were much more difficult for me. The terrain is very rough compared to out west where its smooth.