Planning for the weather is a good way to make your trip to Oshima-gun Amagi-cho relaxing and enjoyable, especially when you're splurging. The hottest months are usually August and July with an average temp of 82°F, while the coldest months are January and February with an average of 63°F. The rainiest months in Oshima-gun Amagi-cho are June, May, July, and August, with each month seeing an average of 12 inches of rainfall.