Weather is probably a major factor when you plan your trip to Naoshima, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually August and July with an average temp of 77°F, while the coldest months are January and February with an average of 46°F. The rainiest months in Naoshima are July, June, September, and August, with each month seeing an average of 7 inches of rainfall.