If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Ibusuki: The hottest months are usually August and July with an average temp of 79°F, while the coldest months are January and February with an average of 54°F. The rainiest months in Ibusuki are June, July, May, and September, with each month seeing an average of 16 inches of rainfall.