Weather will likely play an important role when you plan your trip to Shiroishi, 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 22°C, while the coldest months are February and January, with an average of 3°C. The rainiest months in Shiroishi are September, August, July and October, with each month seeing an average of 203 mm of rainfall.