Clanwilliam normally receives about 274mm of rain per year and because it receives most of its rainfall during winter it has a Mediterranean climate. The chart below (lower left) shows the average rainfall values for Clanwilliam per month. It receives the lowest rainfall (3mm) in February and the highest (57mm) in June. The monthly distribution of average daily maximum temperatures (centre chart below) shows that the average midday temperatures for Clanwilliam range from 17.9°C in July to 31.3°C in February. The region is the coldest during July when the mercury drops to 5.8°C on average during the night. Consult the chart below (lower right) for an indication of the monthly variation of average minimum daily temperatures.