Taking the local weather in Diamond Lake into account is an important factor for planning your visit, especially if you plan to spend your trip by the pool. The hottest months are usually July and August, with an average temperature of 18°C, while the coldest months are February and January, with an average of -2°C. The snowiest months in Diamond Lake are January, December, February and March, with each month seeing an average of 28 cm of snowfall.