Planning for the weather is a good way to make your trip to Akasaki Onsen relaxing and enjoyable, especially when you're splurging. The hottest months are usually August and July, with an average temperature of 24°C, while the coldest months are January and February, with an average of 5°C. The rainiest months in Akasaki Onsen are July, September, August and December, with each month seeing an average of 258 mm of rainfall.