Planning for the weather is an important factor for making your trip to Kinugawa Onsen a success, especially when you’re splurging. The hottest months are usually August and July with an average temp of 70°F, while the coldest months are January and February with an average of 34°F. The rainiest months in Kinugawa Onsen are July, September, October, and June, with each month seeing an average of 10 inches of rainfall.