Other facts from our historical weather data: Which is the hottest month in St Mary? August has an average maximum temperature of 32°C (90°F) and is the hottest month of the year. Which is the coolest month in St Mary? The coolest month is February with an average maximum temperature of 28°C (82°F). Which is the wettest month in St Mary? October tops the wettest month list with 143mm (5.6 in) of rainfall. Which is the driest month in St Mary? February is the driest month with 55mm (2.2 in) of precipitation. Which is the sunniest month in St Mary? July is the sunniest month with an average of 264 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.