If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Hekinan: The hottest months are usually August and July, with an average temperature of 25°C, while the coldest months are January and February, with an average of 7°C. The rainiest months in Hekinan are July, September, June and October, with each month seeing an average of 236 mm of rainfall.