Before you post a question about the weather in China, please read the following article.

China is a big country and the temperature will vary greatly depending on where you are. For example in winter the difference between the north and the south can be as much as 40 degrees celcius (70 degrees F).

Weather is unpredictable. Nobody knows what the weather will be in a specific place next month or even next week. 

In the rain season you may get sunny days or get rain in the dry season. It is a random thing. Nobody knows for sure.

Do not ask about what clothes to wear. Check the weather and make your own decision. Depending where you come from, your resistance to cold or hot humidity is different from other posters. Someone from a tropical climate may need a jacket in 20-degree weather while someone from Canada will find that a t-shirt is fine. Only you know what you should wear for a particular climate. In the spring and fall, the weather may vary a lot during the day. It is best to dress with several layers so you can adjust during the day.

Is it too cold or too hot? It never is. People live there and survive. You will too if you dress appropriately. 

You want to know what the temperature normally is for a specific month? Instead of getting anecdotal comments ("I was in Shanghai a few years ago and it was 25 degrees in January and people walked around in shorts - but I know this is not typical") rely on historical statistics. Weather websites have this.

You want to know what the weather forecast is for next week. To answer you, people need to consult a weather website. So no point asking, check it yourself. Members who happen to be there can only comment about the weather now.

Here are some weather websites:

http://www.worldweather.org/001/m001.htm 

http://www.weather.com 

http://www.wunderground.com/  -  this one will give you historical stats. Towards the buttom of the page see "History and almanac" Choose the dates of your trip. They also have a monthly view.

http://local.msn.com/weather.aspx - this one will also give you monthly averages and well as rainfall stats. 

http://www.weatherchina.org/ -  lots of China locations, over 2000

Remember, you need to check for every city.