How cold is it at IIT Mandi?

The climate at IIT Mandi does not drop extremely and thus it's bearable in winter. 

• The climate is moderate from August till Mid October. After mid-October, you will witness a drop in the temperatures. But the hostels of IIT Mandi have great insulation facilities so you dont have to worry much about the winters. 
• Vacations start from Dec to Feb mid so you are able to escape the extreme temperatures mostly. The only pain is waking up early in the morning at 8 a.m
• Second semester starts in mid-February during which the climate usually remains cool till March.
• After March, the temperature starts rising again and the temperature stays moderate till May. the temperature starts to rise up again. In summer, days will be warm but nights are pretty decent.

Overall, you won't have to deal with extremely cold conditions at IIT Mandi so rest your worries in place.