Other facts from our historical weather data: Which months have the greatest rainfall in Westhaven? Most rainfall (rainy season) is seen in January, February, March, November and December. Does Westhaven have a dry season? Yes, the months of July and August are very dry. Which is the warmest month in Westhaven? September has an average maximum temperature of 18°C (64°F) and is the warmest month of the year. Which is the coldest month in Westhaven? The coldest month is December with an average maximum temperature of 12°C (54°F). Which is the wettest month in Westhaven? December tops the wettest month list with 262mm (10.3 in) of rainfall. Which is the driest month in Westhaven? August is the driest month with 5mm (0.2 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.