Other facts from our historical weather data: Which is the warmest month in Grange? August has an average maximum temperature of 19°C (66°F) and is the warmest month of the year. Which is the coldest month in Grange? The coldest month is February with an average maximum temperature of 9°C (48°F). Which is the wettest month in Grange? December tops the wettest month list with 138mm (5.4 in) of rainfall. Which is the driest month in Grange? April is the driest month with 96mm (3.8 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.