I'm keen to go Taipei in mid September.

According to the previous statistics, the possibility of typhoon would be lower. There may have several rainy days during that periof of time. But it won't influence the sightseeing a lot. You are advised to prepare light jackets, T-shirts, jeans and pants. Have fun!

Hi, there is high possibility that typhoon may strike the area in late Sep. Generally, it may rains frequently but lightly in mid Sep. It can be safe to visit. Anyway, you are still suggested to check ahead the weather forecasts in case.