In December, the weather in Heligoland is typically cold. Average daily high temperature in December is about 6 degrees above zero. On average, Heligoland has 18 rainy, 6 cloudy, 6 partly cloudy, 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 Heligoland.