Travelling in May in Taipei

Hi,
I am planning to visit Taiwan on an organised tour in May.
As I have read the weather conditions for May, it is going to be lots of rain and showers.
Does it make any difference if I choose to travel in the early May, mid of May?
The rain will definitely destroy your holiday mood and plans as I heard from friends that the showers can be quite heavy in the month of May.
Any advice on this is greatly appreciated.
Thank you for your precious time in reading and replying to my inquiry.
Have a nice day.
Francis