Hi, I would like to ask when is the best time to go Taiwan?

Considering the weather condition, the best travel period there shall be Oct. to Mar. in the next year. So it is ok to go there around end of Dec. Don't worry!

It won't be cold then and the average temp may be 13-15℃. You can take along a relatively thick jacket and jeans. While sometimes, it may rain a little, so prepare simple rainy gear!