Weather will likely play an important role when you plan your trip to Adak Island, 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 48°F, while the coldest months are January and February with an average of 36°F. The snowiest months in Adak Island are January, March, December, and February, with each month seeing an average of 25 inches of snowfall.