Weather is probably a major factor when you plan your trip to Tancook Islands, and keep 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 temp of 59°F, while the coldest months are January and February with an average of 27°F. The snowiest months in Tancook Islands are February, January, December, and April, with each month seeing an average of 12 inches of snowfall.