It has been observed that transformer buchholz relay produce an alarm in winter. Can any one suggest why exactly this is happening in winter.

Transformer all parameters are normal, oil level is also normal, no gas accumulation is seen yet in winter alarm pops up.

- Can any one suggest to check what precautions can be taken to avoid having this alarm?
- What could be the reason of this alarm?
- What further actions to be taken to investigate the actual root cause of this alarm?