Weather will likely play an important role when you plan your trip to Hachijo, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually August and September, with an average temperature of 26°C, while the coldest months are January and February, with an average of 14°C. The rainiest months in Hachijo are June, October, September and March, with each month seeing an average of 316 mm of rainfall.