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 Suhara Onsen: 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 8°C. The rainiest months in Suhara Onsen are July, June, September and October, with each month seeing an average of 219 mm of rainfall.