Weather is probably a major factor when you plan your trip to Tancook Islands, 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 15°C, while the coldest months are January and February, with an average of -3°C. The snowiest months in Tancook Islands are February, January, December and April, with each month seeing an average of 31 cm of snowfall.