If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Vadnais Heights: The hottest months are usually July and August, with an average temperature of 20°C, while the coldest months are January and February, with an average of -6°C. The snowiest months in Vadnais Heights are March, February, December and January, with each month seeing an average of 16 cm of snowfall.