From time-to-time the China climate is hit by tropical cyclones. However China is such a large country that you aren't very likely to encounter one of these storms. 

Our winter months are the most peaceful months in China. Up north it's cold, Beijing's daytime temperatures are usually around freezing, however the sky is a beautiful blue and it's a great time to take pictures. South-western China (Sichuan and Yunnan provinces) has mild temperatures in the lower lying areas and this area is great for travel. 

Clothing
Bring along layers of clothing: thin shirts that you can wear one on top of another, several vests or fleece sweater with zippers, anything that you can put on or take off easily. If you're travelling through China between October and April you'll also need gloves, a scarf and a warm coat. Proper walking shoes with a good grip are necessary for the 10km walk over the Great Wall of China. Chinese are not used to seeing much bare skin, so be sure to keep your shoulders and knees covered when visiting temples and other holy places.