The Average Monthly Weather Conditions in the past 10 years (2008-2018)
The average temperature of Yakushima is a mild 20 degree. However, be aware of the temperature differences in elevation, higher the altitude lower the temperature. In the mountains temperature decreases 0.7 degrees per 100 meters.
There is also a big difference in temperature between day and night, especially during spring and autumn.
I recommend that you bring clothes that you can layer to adjust for the weather and climate on Yakushima.
We would like you to know that the mountains will occasionally have heavy rainfall. It is said the annual precipitation of Yakushima is the heaviest in Japan. After a heavy rain, the creeks will be swollen and very dangerous. Please be careful.