Other facts from our historical weather data: When is winter in Mont-de-Lans? The coldest season / winter is in the following months: January, February and December. Which is the warmest month in Mont-de-Lans? August has an average maximum temperature of 20°C (68°F) and is the warmest month of the year. Which is the coldest month in Mont-de-Lans? The coldest month is January with an average maximum temperature of -1°C (30°F). Which is the wettest month in Mont-de-Lans? November tops the wettest month list with 144mm (5.7 in) of rainfall. Which is the driest month in Mont-de-Lans? August is the driest month with 102mm (4 in) of precipitation. Which is the sunniest month in Mont-de-Lans? July is the sunniest month with an average of 288 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.