Overview: Osaka In Osaka, Japan, you can experience a temperate climate with distinct seasonal transitions. Daytime temperatures usually range between 9 °C (48 °F) in the coldest month of January to a peak of 33 °C (91 °F) in the warmest month of August. The least amount of rainfall typically occurs in January, with an average of 8 days experiencing precipitation, while July often has the highest number of rainy days, totaling 14 days. Nighttime temperatures vary from a chilly 2 °C (36 °F) in January to a balmy 25 °C (76 °F) in August. The city also offers an interesting variation in wind speeds and sunshine hours throughout the year.