Having a good idea of the weather in Yunishigawa Onsen will help you enjoy your stay to the fullest. The hottest months are usually August and July, with an average temperature of 17°C, while the coldest months are January and February, with an average of -2°C. The rainiest months in Yunishigawa Onsen are July, August, September and June, with each month seeing an average of 303 mm of rainfall.