I want to visit Taipei in Mar 1 or Mar 15 for 5 days. How is the weather during those dates?

During that time, the lowest temp would be 13-15C and the highest temp is 26-28C. So you can prepare both long-sleeved and short-sleeved shirts as well as a light coat. Generally, it may rain for some days, but not heavy. An umbrella or simple rainy gear is also suggested to be taken along.