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 Chikuma: The hottest months are usually August and July, with an average temperature of 20°C, while the coldest months are January and February, with an average of -1°C. The rainiest months in Chikuma are July, August, September and June, with each month seeing an average of 239 mm of rainfall.