Actually it entirely depends upon the season when you are travelling in North Bengal. If you are lucky, you can experience snow fall in high altitude area like Sandakphu, Phalut, Sukiapokhri during winter season when temperature in these places goes down to subzero. As per recorded data, the last time Darjeeling and its surrounding got snow fall was on 14th Feb 2008. So travelling North Bengal during January to February brings you the probability to experience snow fall.