I took the last cold days in the Sauerland during a weekend trip. I made a lot of winter errors. The first was leaving my bottle insulation at home. At the -8 °C the bottles were frozen after very short time and I needed to carry a 0,5l bottle at the body. Luckily I had enough streams to refill the bottle. The second was not carrying a fleeze jacket and cooling out a lot even while hiking :( The third was an inflatable mat which I didn’t check at home. For some reason it lost air and I had to refill it every hour. Later in the morning after the -10°C night the valve was completely frozen and I was unable to open it at first.
The fourth was to not take camera and mobile batteries into my sleeping bag, leading to dead devices. However warming the batteries brought them back to life. The fifth was not planning enough food, especially not enough high sugar food which brinks energy. The sixth was leaving the spikes at home as most of the time the ground was covered in ice.
Besides all these errors I truly enjoyed the trip. Hiking in the winter is something special. The dusk, night and dawn with a no-cloud-sky was wonderful, as you might see in the images. Some information: It takes 10-10:30 minutes melting 1l of snow with a caldera cone.