Regarding the summer in Frankfurt, even in the hottest month of July-August, highs are around 25 degrees C. December-February is particularly cold, with lows occasionally go below freezing. Rain falls throughout the year.

Reference Tokyo's climate Weather Altas "Monthly weather forecast and climate Tokyo, Japan" Retrieved June 5, 2020, from https://bit.ly/3dBbSTF Frankfurt's climate Weather Altas "Monthly weather forecast and climate Frankfurt, Germany" Retrieved June 9, 2020, from https://bit.ly/2AjDRZD Frankfurt's humidity Climatemps. Com　Retrieved June 9, 2020, from　https://bit.ly/303b3yE