Other facts from our historical weather data: Which months have the greatest rainfall in Saint-Louis? Most rainfall (rainy season) is seen in September and October. Which is the warmest month in Saint-Louis? September has an average maximum temperature of 29°C (84°F) and is the warmest month of the year. Which is the coldest month in Saint-Louis? The coldest month is February with an average maximum temperature of 27°C (81°F). Which is the wettest month in Saint-Louis? October tops the wettest month list with 159mm (6.3 in) of rainfall. Which is the driest month in Saint-Louis? March is the driest month with 48mm (1.9 in) of precipitation. Which is the sunniest month in Saint-Louis? August is the sunniest month with an average of 248 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.