Weather will likely play an important role when you plan your trip to Hitachi, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually August and July, with an average temperature of 23°C, while the coldest months are January and February, with an average of 5°C. The rainiest months in Hitachi are September, July, October and June, with each month seeing an average of 199 mm of rainfall.