Other facts from our historical weather data: Which months have the greatest rainfall in Belfast? Most rainfall (rainy season) is seen in September and October. Which is the warmest month in Belfast? August has an average maximum temperature of 30°C (86°F) and is the warmest month of the year. Which is the coldest month in Belfast? The coldest month is February with an average maximum temperature of 27°C (81°F). Which is the wettest month in Belfast? October tops the wettest month list with 191mm (7.5 in) of rainfall. Which is the driest month in Belfast? February is the driest month with 52mm (2 in) of precipitation. Which is the sunniest month in Belfast? 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.