Weather is probably a major factor when you plan your trip to Shikine-jima, 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 25°C, while the coldest months are January and February, with an average of 12°C. The rainiest months in Shikine-jima are June, October, September and July, with each month seeing an average of 289 mm of rainfall.