Taking into account the local weather in Shinjo is an important factor for planning your visit, especially if you plan to spend your trip poolside. The hottest months are usually August and July with an average temp of 68°F, while the coldest months are February and January with an average of 31°F. The rainiest months in Shinjo are July, August, December, and September, with each month seeing an average of 9 inches of rainfall.