Though weather is just one factor, it can really affect your travel plans, especially when you're planning an extended stay in Oshima-gun China-cho. 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 64°F. The rainiest months in Oshima-gun China-cho are June, May, August, and July, with each month seeing an average of 12 inches of rainfall.