In Konstanz, the climate is warm and temperate. The rainfall in Konstanz is significant, with precipitation even during the driest month. Though inland, being at the shores of Constance Lake (Bodensee) gives the city pleasant summers. The winters are chilly, but not too cold.
The best time to visit Konstanz would be in the months of June, July, August and September (summer months and beginning autumn). The temperatures are comfortably warm with low precipitations and clear visibility, allowing you to have an unhindered experience of the city.