What's the weather like in summer in Xining, Qinghai?

Summer is particularly cool, the temperature is around 20 degrees, but the temperature difference between day and night is relatively large, and there are obvious differences between indoor and outdoor. Outside, you can wear short sleeves, but you should cover yourself with a quilt. Because summer is cool, it is called summer capital. In addition, there are no fans and air conditioners here, because there are basically no mosquitoes and flies in Xining in summer. In short, Xining is suitable for summer.