Weather is probably a major factor when you plan your trip to Janov nad Nisou, but bear in mind that cheaper options are usually available when the weather isn't as good. 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 0°C. The snowiest months in Janov nad Nisou are December, January, November and February, with each month seeing an average of 14 cm of snowfall.