Other facts from our historical weather data: Which is the warmest month in Oulu? July has an average maximum temperature of 21°C (70°F) and is the warmest month of the year. Which is the coldest month in Oulu? The coldest month is February with an average maximum temperature of -4°C (25°F). Which is the wettest month in Oulu? July tops the wettest month list with 84mm (3.3 in) of rainfall. Which is the driest month in Oulu? March is the driest month with 35mm (1.4 in) of precipitation. Which is the sunniest month in Oulu? June is the sunniest month with an average of 299 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.