Weather will likely play an important role when you plan your trip to Yagishiri Island, 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 18°C, while the coldest months are January and February, with an average of -1°C. The snowiest months in Yagishiri Island are January, March, February and December, with each month seeing an average of 60 cm of snowfall.