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 Tsumagoi: The hottest months are usually August and July, with an average temperature of 19°C, while the coldest months are January and February, with an average of -1°C. The rainiest months in Tsumagoi are July, August, June and September, with each month seeing an average of 246 mm of rainfall.