Other facts from our historical weather data: Which is the warmest month in Rjukan? July has an average maximum temperature of 18°C (64°F) and is the warmest month of the year. Which is the coldest month in Rjukan? The coldest month is January with an average maximum temperature of -3°C (27°F). Which is the wettest month in Rjukan? July tops the wettest month list with 128mm (5 in) of rainfall. Which is the driest month in Rjukan? March is the driest month with 71mm (2.8 in) of precipitation. No idea where to travel to this year? We have a tool that recommends destinations based on your ideal conditions. Find out where to go with our weather planner.