Other facts from our historical weather data: Which is the warmest month in St. Agnes ? 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. Agnes ? The coldest month is February with an average maximum temperature of 11°C (52°F). Which is the wettest month in St. Agnes ? November tops the wettest month list with 104mm (4.1 in) of rainfall. Which is the driest month in St. Agnes ? May is the driest month with 66mm (2.6 in) of precipitation. Which is the sunniest month in St. Agnes ? May is the sunniest month with an average of 222 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.