If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Changwon: The hottest months are usually August and July with an average temp of 74°F, while the coldest months are January and December with an average of 41°F. The rainiest months in Changwon are July, August, September, and June, with each month seeing an average of 8 inches of rainfall.