Other facts from our historical weather data: When is winter in Bolla? The coldest season / winter is in the following months: January, February, March and December. Which is the warmest month in Bolla? July has an average maximum temperature of 16°C (61°F) and is the warmest month of the year. Which is the coldest month in Bolla? The coldest month is February with an average maximum temperature of -1°C (30°F). Which is the wettest month in Bolla? September tops the wettest month list with 151mm (5.9 in) of rainfall. Which is the driest month in Bolla? April is the driest month with 94mm (3.7 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.