Other facts from our historical weather data: Which is the warmest month in Coleraine? August has an average maximum temperature of 17°C (63°F) and is the warmest month of the year. Which is the coldest month in Coleraine? The coldest month is February with an average maximum temperature of 9°C (48°F). Which is the wettest month in Coleraine? November tops the wettest month list with 134mm (5.3 in) of rainfall. Which is the driest month in Coleraine? May is the driest month with 80mm (3.1 in) of precipitation. Which is the sunniest month in Coleraine? May is the sunniest month with an average of 203 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.