Is there any restriction for the Winter tour?

Yes. According to the regulations, February and March are off-limits to international visitors to Tibet. Tibet will be closed for the Tibetan New Year over those two months.

Aside from that, low temperatures and a lot of snow cause several locations to be closed to tourists. Avoid specific mountainous and high-altitude locations, such as Ngari and Namtso Lake. Furthermore, extreme cold and snowfall make specific locations inaccessible to tourists throughout the winter. You are not advised to visit specific mountainous and high-altitude locations, such as Namtso Lake and Ngari.