If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Vantaa: The hottest months are usually July and August, with an average temperature of 16°C, while the coldest months are January and February, with an average of -3°C. The snowiest months in Vantaa are January, March, December and November, with each month seeing an average of 28 cm of snowfall.