We stayed in Piburger for 4 nights in January 2020. The lake was absolutely beautiful with solid ice covering it, perfect for ice skating (an ice hockey too). We had around 6cm of fresh snow fall on night 2 which transformed the lake into a winter wonderland...especially for visiting Australians! A man on a tractor cleared a skating track around the entire circumference of the lake, and through the center also. Ice skates can be hired for 4 Euro. There are pleanty of hiking trails and the snow is no problem. A simple walk around the edge of the lake will take you about an hour if you take your time to take photos, enjoy the scenery and stop to watch the (oversize) squirrels eat seed from the various bird houses. Highly rated in winter!