If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Setouchi: The hottest months are usually August and July with an average temp of 80°F, while the coldest months are January and February with an average of 61°F. The rainiest months in Setouchi are June, May, August, and September, with each month seeing an average of 13 inches of rainfall.