Planning for the weather is a good way to make your trip to Mělník relaxing and enjoyable, especially when you’re splurging. The hottest months are usually July and August, with an average temperature of 18°C, while the coldest months are January and February, with an average of 1°C. The snowiest months in Mělník are December, November, January and February, with each month seeing an average of 19 cm of snowfall.