Planning for the weather is an important factor for making your trip to Mitsunashi a success, especially when you're splurging. The hottest months are usually August and July, with an average temperature of 20°C, while the coldest months are February and January, with an average of -1°C. The rainiest months in Mitsunashi are July, August, December and September, with each month seeing an average of 205 mm of rainfall.