Other facts from our historical weather data: When is summer in Quincy?The hottest season / summer takes place in June, July, August and September. Which is the warmest month in Quincy? July has an average maximum temperature of 30°C (86°F) and is the warmest month of the year. Which is the coldest month in Quincy? The coldest month is January with an average maximum temperature of 2°C (36°F). Which is the wettest month in Quincy? June tops the wettest month list with 140mm (5.5 in) of rainfall. Which is the driest month in Quincy? January is the driest month with 34mm (1.3 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.