Wetter Schnee
In short
Wetter Schnee is a German term for wet snow, which occurs when the temperature is near freezing. This type of snow contains a high amount of liquid water.
In plain words
It happens when the air is just warm enough that the snowflakes start to melt. Instead of being dry and powdery, the snow becomes heavy, sticky, and clumped together.
A simple example
If you squeeze a handful of wet snow, it will stay in a solid ball. Dry snow would simply crumble and fall apart.
Why it matters
Wet snow is much heavier than dry snow, which can cause tree branches to snap. It also makes driving difficult because it turns into slush on the roads.
Easy to mix up
Do not confuse it with powder snow, which is very dry and light.