Other facts from our historical weather data: Which is the warmest month in Cemaes Bay? August has an average maximum temperature of 19°C (66°F) and is the warmest month of the year. Which is the coldest month in Cemaes Bay? The coldest month is February with an average maximum temperature of 9°C (48°F). Which is the wettest month in Cemaes Bay? November tops the wettest month list with 126mm (5 in) of rainfall. Which is the driest month in Cemaes Bay? May is the driest month with 63mm (2.5 in) of precipitation. 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.