Other facts from our historical weather data: When is the rainy season in Interlaken? Rainy season in Interlaken occurs in the months of May, June, July, August and September. When is winter in Interlaken? The coldest season / winter is in the following months: January, February and December. Which is the warmest month in Interlaken? July has an average maximum temperature of 18°C (64°F) and is the warmest month of the year. Which is the coldest month in Interlaken? The coldest month is January with an average maximum temperature of -2°C (28°F). Which is the wettest month in Interlaken? July tops the wettest month list with 226mm (8.9 in) of rainfall. Which is the driest month in Interlaken? March is the driest month with 129mm (5.1 in) of precipitation. Which is the sunniest month in Interlaken? July is the sunniest month with an average of 219 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.