Other facts from our historical weather data: Which is the warmest month in Castle Forbes Bay? February has an average maximum temperature of 20°C (68°F) and is the warmest month of the year. Which is the coldest month in Castle Forbes Bay? The coldest month is July with an average maximum temperature of 12°C (54°F). Which is the wettest month in Castle Forbes Bay? August tops the wettest month list with 91mm (3.6 in) of rainfall. Which is the driest month in Castle Forbes Bay? March is the driest month with 62mm (2.4 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.