May 1 What should I wear to Shanghai? How about short sleeves?

I heard that it may be cold in Shanghai these days, and the temperature difference between morning and evening is large. It is best to bring some thick clothes. If you don't have clothes, you can bring more money to Shanghai to buy them, but things in Shanghai are very expensive. Because the temperature in Shanghai this year is very unstable, sometimes cold and sometimes hot. For example, the day before yesterday, I could wear short sleeves. Yesterday, the weather suddenly turned cold, so I am wearing a sweater today. You'd better check the weather forecast before you come.