Weather is probably a major factor when you plan your trip to Yonezawa, 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 69°F, while the coldest months are January and February with an average of 31°F. The rainiest months in Yonezawa are July, December, August, and June, with each month seeing an average of 9 inches of rainfall.