Other facts from our historical weather data: When is winter in Namsos? The coldest season / winter is in the following months: January, February and December. Which is the warmest month in Namsos? July has an average maximum temperature of 20°C (68°F) and is the warmest month of the year. Which is the coldest month in Namsos? The coldest month is February with an average maximum temperature of 2°C (36°F). Which is the wettest month in Namsos? September tops the wettest month list with 156mm (6.1 in) of rainfall. Which is the driest month in Namsos? May is the driest month with 96mm (3.8 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.