Well, I would guess you are seeing an impact of climate destabilization. This is a product of carbon and methane emissions into the atmosphere over the past two centuries, predominantly from the burning of fossil fuels, increasing the heat retention in the oceans and atmosphere. While it is not possible to say with confidence if this particular temperature anomaly you mention, is an actual anomaly (outside the normal temperature range for the time of year) or just a random weather event, so we cannot say with certainty that it is or is not directly caused by climate destabilization. But the chances it is are increasing year-on-year. Other notable temperature anomalies reported recently include 20 degree celsius higher average temperature in arctic regions during November and the extreme temperatures experienced across India last spring. We are cooking but governments still want to dig and burn coal which will make the matter worse.
In winter it can be this cold as Shillong is sitauted 1500 - almost 2000 m above sea level. The coldest recorded night temperature since 1970 in the months November - February has been -3.3C. The very moderate climate was also the reason why the British made Shillong a hill station.