Planning for the weather is a good way to make your trip to Jianyang relaxing and enjoyable, especially when you’re splurging. The hottest months are usually August and July with an average temp of 78°F, while the coldest months are January and December with an average of 51°F. The rainiest months in Jianyang are July, August, June, and September, with each month seeing an average of 8 inches of rainfall.