If you're looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Obanazawa: The hottest months are usually August and July, with an average temperature of 20°C, while the coldest months are February and January, with an average of 0°C. The rainiest months in Obanazawa are July, August, December and September, with each month seeing an average of 234 mm of rainfall.