Weather is probably a major factor when you plan your trip to Sumita, 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 21°C, while the coldest months are February and January, with an average of 2°C. The rainiest months in Sumita are September, October, August and July, with each month seeing an average of 188 mm of rainfall.