Weather will likely play an important role when you plan your trip to Unalaska, 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 49°F, while the coldest months are January and March with an average of 34°F. The snowiest months in Unalaska are December, February, March, and January, with each month seeing an average of 22 inches of snowfall.