Planning for the weather is a good way to make your trip to Miyazaki relaxing and enjoyable, especially when you’re splurging. The hottest months are usually August and July with an average temp of 78°F, while the coldest months are January and February with an average of 51°F. The rainiest months in Miyazaki are June, July, September, and August, with each month seeing an average of 15 inches of rainfall.