Other facts from our historical weather data: When is summer in Cincinnati?The hottest season / summer takes place in June, July, August and September. Which is the warmest month in Cincinnati? August has an average maximum temperature of 30°C (86°F) and is the warmest month of the year. Which is the coldest month in Cincinnati? The coldest month is February with an average maximum temperature of 4°C (39°F). Which is the wettest month in Cincinnati? April tops the wettest month list with 133mm (5.2 in) of rainfall. Which is the driest month in Cincinnati? August is the driest month with 70mm (2.8 in) of precipitation. Which is the sunniest month in Cincinnati? June is the sunniest month with an average of 277 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.