Hellos.

I am planning a Taiwan trip either on the 22Oct to 26Oct or 28Oct to 02Nov or on 04Nov to 09Nov. I want to go over to shop for clothes to wear in Singapore so I don't really want to buy thick clothes. If i am going between those dates can I still find summer clothes? And if I'm going between those dates can I wear sleeveless clothes or tshirt and shorts? Or is it better to wear jeans?

Thank you! =)