Other facts from our historical weather data: Which is the warmest month in Halwell? August has an average maximum temperature of 20°C (68°F) and is the warmest month of the year. Which is the coldest month in Halwell? The coldest month is February with an average maximum temperature of 10°C (50°F). Which is the wettest month in Halwell? November tops the wettest month list with 103mm (4.1 in) of rainfall. Which is the driest month in Halwell? July is the driest month with 59mm (2.3 in) of precipitation. Which is the sunniest month in Halwell? May is the sunniest month with an average of 222 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.