Planning for the weather is a good way to make your trip to Jiujiang relaxing and enjoyable, especially when you’re splurging. The hottest months are usually August and July with an average temp of 77°F, while the coldest months are January and December with an average of 44°F. The rainiest months in Jiujiang are June, July, May, and April, with each month seeing an average of 12 inches of rainfall.