Other facts from our historical weather data: Which months have the greatest rainfall in Duncans? Most rainfall (rainy season) is seen in May, September and October. Which is the hottest month in Duncans? July has an average maximum temperature of 32°C (90°F) and is the hottest month of the year. Which is the coolest month in Duncans? The coolest month is February with an average maximum temperature of 28°C (82°F). Which is the wettest month in Duncans? September tops the wettest month list with 172mm (6.8 in) of rainfall. Which is the driest month in Duncans? February is the driest month with 49mm (1.9 in) of precipitation. Which is the sunniest month in Duncans? April is the sunniest month with an average of 253 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.