What is the weather like from Sept to June in Yinchuan?

Do you mean from Sept to the next June?
If so, you will prepare clothes for all the seasons.
You should take more clothes for spring and autumn, long-sleeved shirts, thin overcoat and jeans are ok. In winter, it will be quite cold, you need to wear down jackets and boots. In June, you may need to wear T-shirts and shorts.