Weather will likely play an important role when you plan your trip to Miyakejima, and keep 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 temp of 78°F, while the coldest months are January and February with an average of 55°F. The rainiest months in Miyakejima are June, October, September, and November, with each month seeing an average of 12 inches of rainfall.