Hey Bro, If you are person who loves winters and snow, then you are on a right place... Go Ahead... The best and easiest means of reaching Tawang from Delhi would be through flight. The nearest Domestic Airport is Salonibari Airport, Tezpur, roughly 6 hour drive from Tawang. It is well connected to Kolkata and Guwahati through Air India flight. The nearest International Airport from Tawang is Lokpriya Gopinath Bordoloi International Airport, Guwahati, roughly 480 Kms from Tawang. Happy Travelling Bro!!!
It is viable but not recommended. The temperatures in Tawang during December-January dip pretty low (between 2C-10C). The coldest month is January. Hence, very few tourists venture to Tawang during this time. Another problem you may face are road blocks caused due to heavy snowfall, which make it difficult to move in and out of the town area and thereby may restrict you from seeing certain tourist spots. However, if you just want to experience snow, enjoy the frozen lakes, and dont mind the solitude, then by all means come in December. To reach Tawang from Delhi: Tawang does not have an airport or railway station, so if youre coming by air, youll have to fly to the nearest airport, which is Tezpur Airport in Assam from either Kolkata or Guwahati. Similarly, you will have to take a train from Delhi to Tezpur railway station. Travel from here onwards is by road. There are plenty of private and shared cabs or buses that go to Tawang, which is close to a 12-hour ride. A friend visited Tawang last year by going through a travel agency called TourGenie based in Sikkim. She had a wonderful time. You may want to check them out.