Weather is only one factor, but it can really affect your travel plans, especially when you are planning a longer stay in Dayton. The hottest months are usually July and August, with an average temperature of 19°C, while the coldest months are January and December, with an average of -4°C. The snowiest months in Dayton are April, January, February and December, with each month seeing an average of 44 cm of snowfall.