Other facts from our historical weather data: When is winter in St. John's? The coldest season / winter is in the following months: January, February and March. Which is the warmest month in St. John's? August has an average maximum temperature of 20°C (68°F) and is the warmest month of the year. Which is the coldest month in St. John's? The coldest month is February with an average maximum temperature of 1°C (34°F). Which is the wettest month in St. John's? December tops the wettest month list with 136mm (5.4 in) of rainfall. Which is the driest month in St. John's? June is the driest month with 77mm (3 in) of precipitation. Which is the sunniest month in St. John's? July is the sunniest month with an average of 216 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.