What's the weather like in Shanghai in May and June? What should I wear?

I suggest you wear a coat and a thin sweater at the beginning of May and a T-shirt at the end of the month. Because May is a month with drastic annual temperature changes, it is estimated that there will be a temperature difference of nearly 20 degrees from early spring at the beginning of the month to early summer at the end of the month. Strictly speaking, in Daqing, there is only one month in spring, May. There is only one month in autumn, October. Everything else is winter and summer.