In April, the weather in Rjukan is typically cold. Average daily high temperature in April is about 3 degrees above zero. On average, Rjukan has 11 rainy, 7 cloudy, 6 sunny, 5 partly cloudy, and 1 snowy day in April. The rains are usually moderate. April as well as May, June, July, and August is considered the most uncomfortable time to visit Rjukan.