Traveling Hampta pass would not be a safe and easy option in winters, Would recommend you to not to plan because in this season you will not be able to have permit as well as entry for going there is permitted, It's a huge block ways in between the ways , You will be able to visit till Solang valley & Gulaba , after that their are many restrictions. I would like to recommend you to go there after April or May
I am currently at sethan and yestrday itself i have completed my batch . and next batch is on 7 feb . i am sure we can do it doesnt matter about the weather because hampta pass is a moderate trek as well not that risky . i have been doing my treks mostly in winters because most people question me th