Yes, Beijing and Shanghai are incredibly hot in the summer. I think the average summer temperature in Beijing is 34 Celsius. Shanghai is about the same. But if August is the only time you can go, then don't let the heat stop you. Just plan to stay indoors as much as you can, or visit places in the evening, when it's (slightly) cooler.
I was in Shanghai in late September a few years ago and it was still extremely hot and humid then.
There is long list of touring area. But its exited and all are famous but all are Asian destination.
It's pretty hot and humid in Shanghai right now!! But can definitely still do stuff. Just carry a drinking water bottle with you at all times and stay hydrated, and also it's handy to have a packet of wet wipes, and (or) a wet washcloth (in a zip lock bag is a good idea) to cool off.