What's the weather like in Hangzhou from the second half of September to the end of September (about 15-30)?

It's better than midsummer, but it's basically the feeling of summer. The daily average maximum temperature will still be around 30 degrees, sometimes even above 30 degrees. It will get cold sooner or later. Mainly summer clothes.

However, the late summer is a typhoon-prone season. Typhoons usually land on the southeast coast of Zhejiang and Fujian, and never have a great impact on Hangzhou. At most, there will be a little rain and wind in Hangzhou, but the weather usually lasts 1 or 2 days at this time, so you should also bring 1 or 2 thin long-sleeved clothes.