If you're hoping to get lost in the rain on your romantic getaway, take a look at these details about year-round temperatures in Minamisoma: The hottest months are usually August and July, with an average temperature of 23°C, while the coldest months are January and February, with an average of 4°C. The rainiest months in Minamisoma are September, October, August and July, with each month seeing an average of 209 mm of rainfall.