In December, the weather in Karlskoga is typically freezing. Average daily high temperature in December is about zero. On average, Karlskoga has 12 cloudy, 7 partly cloudy, 5 sunny, 4 rainy, and 3 snowy days in December. The rains are usually moderate. December as well as January, February, March, and April is considered the most uncomfortable time to visit Karlskoga.