Other facts from our historical weather data: Which is the warmest month in Pierowall? August has an average maximum temperature of 15°C (59°F) and is the warmest month of the year. Which is the coldest month in Pierowall? The coldest month is February with an average maximum temperature of 8°C (46°F). Which is the wettest month in Pierowall? November tops the wettest month list with 135mm (5.3 in) of rainfall. Which is the driest month in Pierowall? May is the driest month with 56mm (2.2 in) of precipitation. Which is the sunniest month in Pierowall? May is the sunniest month with an average of 192 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.