I could not find a reliable source that provides the average temperature in Japan in 1945. However, I found some information that might be helpful. According to, January 1945 was the coldest month in Japan with an average temperature of -0.4°C. The average annual temperature was about 12.6°C in the years after 1923 and about 14.8°C in the last years before 2022. It is worth noting that the temperature varies across different regions in Japan. In the northern part of Japan, which includes the island of Hokkaido and the Tohoku region, the climate is predominantly cold and snowy, with long, severe winters and temperatures below freezing. In contrast, Minami-Tori-shima in Tokyo has the highest annual average temperature in Japan, with an annual average temperature of 25.8°C, exceeding the value recorded by all weather stations including Okinawa Prefecture.