Weather will likely play an important role when you plan your trip to Akasaki Onsen, 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 74°F, while the coldest months are January and February with an average of 41°F. The rainiest months in Akasaki Onsen are July, September, August, and December, with each month seeing an average of 10 inches of rainfall.