What's the weather like in the south of Sichuan-Tibet line from mid-late July to early August? Is it hot?

It may be very hot during the day, and strong ultraviolet rays will burn the skin. Remember to take sun protection measures, it will be very cold at night. Because of the large temperature difference between day and night in the plateau area, it is recommended that you make adequate preparations when you go. If you are afraid of high reaction, personally, I suggest you buy some anti-high reaction products, such as Youyi Jianneng, in case of emergency.