I wanna to know will it be alright to go to taipei at 21 sept to 28 sept.. as I going for wedding photo shooting.

Based on the previous records, the average temperature is around 25 to 30C in Sep. It may easily rain in that time.

But the exact detail weather information is hard to tell because it is so early. In my opinion, you can pay attention on the weather forecast before going to arrange your schedule.