Other facts from our historical weather data: When is summer in Billings?The hottest season / summer takes place in June, July, August and September. Does Billings have a dry season? Yes, the months of January, February, November and December are very dry. Which is the warmest month in Billings? July has an average maximum temperature of 32°C (90°F) and is the warmest month of the year. Which is the coldest month in Billings? The coldest month is December with an average maximum temperature of 2°C (36°F). Which is the wettest month in Billings? May tops the wettest month list with 79mm (3.1 in) of rainfall. Which is the driest month in Billings? February is the driest month with 11mm (0.4 in) of precipitation. Which is the sunniest month in Billings? July is the sunniest month with an average of 355 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.