I just walked across the Ringvaart, here in Amsterdam Oost! A brave neighbor, Henk, was out shoveling this morning -- and he confirmed that the ice was already 6 centimeters thick, beneath the blanket of snow from yesterday. He said that he checked things out himself, together with two other grown men creating a combined weight of over 200 kilograms, and the ice was totally safe.
So a spontaneous ice party burst out with kids on skates and sleds, mothers taking pictures, and dogs chasing balls through the snow. It's the way Amsterdam winters are meant to be!