Planning for the weather is an important factor for making your trip to Kirishima a success, 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 8°C. The rainiest months in Kirishima are June, July, May and September, with each month seeing an average of 405 mm of rainfall.