Other facts from our historical weather data: Which is the warmest month in Colwyn Bay? July has an average maximum temperature of 20°C (68°F) and is the warmest month of the year. Which is the coldest month in Colwyn Bay? The coldest month is February with an average maximum temperature of 9°C (48°F). Which is the wettest month in Colwyn Bay? December tops the wettest month list with 103mm (4.1 in) of rainfall. Which is the driest month in Colwyn Bay? May is the driest month with 74mm (2.9 in) of precipitation. Which is the sunniest month in Colwyn Bay? May is the sunniest month with an average of 169 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.