Other facts from our historical weather data: Which months have the greatest rainfall in Bosteri? Most rainfall (rainy season) is seen in June, July, August and September. Which is the warmest month in Bosteri? July has an average maximum temperature of 17°C (63°F) and is the warmest month of the year. Which is the coldest month in Bosteri? The coldest month is January with an average maximum temperature of -3°C (27°F). Which is the wettest month in Bosteri? July tops the wettest month list with 195mm (7.7 in) of rainfall. Which is the driest month in Bosteri? January is the driest month with 57mm (2.2 in) of precipitation. Which is the sunniest month in Bosteri? July is the sunniest month with an average of 308 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.