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 Ejisu: The hottest months are usually January and February, with an average temperature of 28°C, while the coldest months are August and July, with an average of 25°C. The rainiest months in Ejisu are September, June, October and May, with each month seeing an average of 192 mm of rainfall.