September is the beginning time of Autumn weather. The heat, especially in northern China, finally begins to let off. It's also significantly dryer in September than in the summer months. In southern China, the hot and humid weather continues but it is gradually replaced by autumn cooler and drier weather by the end of this month but it can still be very wet.
Clothes to Wear in
It’s a good choice to take some take lightweight, quick-drying clothing when you go out on daytime and it’s necessary having a very light cover such as long sleeve shirt or lightweight sweater in evenings for the weather may be cooler. Remember to bring sun block, sunglasses and sunhat with you.
Travel tips on September
1) Cooling and drying of northern China makes September a great time to visit, especially Beijing.
2) School is back in session in most places so you'll have fewer summer travelers, thus lessening the crowds somewhat.
3) While there's no perfect time to go to central/southern China, it can still be very wet in September, the end of the typhoon season.
4) The week that includes October 1st, is part of a week-long public holiday so travel at the end of September can be quite expensive and difficult to book.