If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Jieyang: The hottest months are usually July and August with an average temp of 81°F, while the coldest months are January and December with an average of 61°F. The rainiest months in Jieyang are June, August, July, and May, with each month seeing an average of 10 inches of rainfall.