Whist it rarely gets particularly cold in most of north India, It affects more chance encountering sub-freezing temperatures in the winter. If you need to supply portable or back-up power halfway up a mountain area, it never hurts or brushes upon starting these diesel engines in cold weather.
Diesel generators can simply be difficult to start in cold weather at 0oC, the battery will typically deliver less than half the current it would at more normal temperatures. The engine fuel and lubricating oil can even become thick or tarry in the middle of a particularly cold snap, which can help to prevent starting altogether.
One way to make sure your back-up power supply will really it will work well or not when the temperature drops are to test it. See if it will start without trouble. Better schedule extra inspection and maintenance sessions during the coldest weather.