Planning for the weather is a good way to make your trip to Jiande relaxing and enjoyable, especially when you're splurging. The hottest months are usually August and July, with an average temperature of 26°C, while the coldest months are January and December, with an average of 8°C. The rainiest months in Jiande are June, July, May and August, with each month seeing an average of 241 mm of rainfall.