Weather will likely play an important role when you plan your trip to Okushiri, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually August and September with an average temp of 68°F, while the coldest months are January and February with an average of 35°F. The snowiest months in Okushiri are January, February, March, and December, with each month seeing an average of 30 inches of snowfall.