I lived in the Hamburg area for many years, and still spend a lot of time there now.

As others have said... it's entirely unpredictable.

All I can really say is that you will usually get some snow some between about November and April (yes, April - I remember waking up to a thick layer of snow one day in mid-April 1996). Some years there is a lot. Some years there is hardly any at all. Some years you get snow in November and Spring-like days in December and January. Some years it's the other way round. I don't remember many years when snow has closed roads or railway lines, but it does happen (it happened in 1979 when I was at college in Hamburg...)

So, as others have said... anything is possible.