Other facts from our historical weather data: Which is the warmest month in Tromsø? July has an average maximum temperature of 17°C (63°F) and is the warmest month of the year. Which is the coldest month in Tromsø? The coldest month is January with an average maximum temperature of -3°C (27°F). Which is the wettest month in Tromsø? September tops the wettest month list with 141mm (5.6 in) of rainfall. Which is the driest month in Tromsø? April is the driest month with 97mm (3.8 in) of precipitation. Which is the sunniest month in Tromsø? May is the sunniest month with an average of 219 hours of sunshine. 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.