Weather is probably a major factor when you plan your trip to Katayamazu, and keep 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 temp of 75°F, while the coldest months are January and February with an average of 42°F. The rainiest months in Katayamazu are December, July, September, and January, with each month seeing an average of 11 inches of rainfall.