We are planning a holiday in Taiwan or Guangxi from 12 dec to 20 dec. what weather can be expected?

The average temperature of Guangxi at that period of time is 52 °F. You can bring your T-shirts and long-sleeved blouse.

TW experiences weather similar to Yunnan, Guangxi and Guangdong provinces.
There is no severe cold in winter. It always welcomes you with its pleasant seasons.
The average temperature of Dec. is 61 °F. It's cool.