Other facts from our historical weather data: Which is the warmest month in Blue River? July has an average maximum temperature of 20°C (68°F) and is the warmest month of the year. Which is the coldest month in Blue River? The coldest month is December with an average maximum temperature of -7°C (19°F). Which is the wettest month in Blue River? November tops the wettest month list with 138mm (5.4 in) of rainfall. Which is the driest month in Blue River? April is the driest month with 79mm (3.1 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.