In December, the weather in Adak Island is typically cold. Average daily high temperature in December is about 2 degrees above zero. On average, Adak Island has 13 partly cloudy, 10 rainy, 6 cloudy, 1 snowy, and 1 sunny day in December. The rains are usually heavy. December as well as January, February, March, and April is considered the most uncomfortable time to visit Adak Island.