Taking into account the local weather in Jablonec nad Nisou is an important factor for planning your visit, especially if you plan to spend your trip poolside. The hottest months are usually July and August with an average temp of 61°F, while the coldest months are January and February with an average of 32°F. The snowiest months in Jablonec nad Nisou are December, January, November, and February, with each month seeing an average of 5 inches of snowfall.