At first I thought that it was very possible as Delhi gets a few days of close to 0 C temperature. But, it happens on sunny (or foggy) days but not on cloudy days. As it has been happening in the last couple of days (the low temperature has been close to 7-8 C), clouds do not allow the sun's heat to escape during the night, so the temperature does not go down that low. This makes the possibility of snow very low.
So, for snow to take place in Delhi, there has to be a string of unlikely events in January. The skies have to be clear for most of the night until early morning. It has to become colder than 0 C. Then clouds have to travel over Delhi in those early morning hours. Then, those clouds have to precipitate and you will get snow.
So, it is possible but very unlikely in the near future, but the way the climate is changing, I wouldn't be too surprised if it snows in Delhi.