Other facts from our historical weather data: Which is the warmest month in Dayton? 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 Dayton? The coldest month is February with an average maximum temperature of 3°C (37°F). Which is the wettest month in Dayton? June tops the wettest month list with 129mm (5.1 in) of rainfall. Which is the driest month in Dayton? February is the driest month with 62mm (2.4 in) of precipitation. Which is the sunniest month in Dayton? July is the sunniest month with an average of 298 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.