Weather is probably a major factor when you plan your trip to Katayamazu Onsen, but bear in mind that cheaper options are usually available when the weather isn't as good. 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 6°C. The rainiest months in Katayamazu Onsen are December, July, September and January, with each month seeing an average of 288 mm of rainfall.