If you're looking forward to lots of outings with your partner, check out these details about year-round temperatures in Obanazawa: 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 Obanazawa are July, August, December, and September, with each month seeing an average of 9 inches of rainfall.