Here, in Belarus, according to the locals, winter also had a very slow start. Even first snow that fell and stayed for more than a day happened only after 1 of January. But now the situation has changed, and there have been many days of up to -20C during a day, and more to come. It may not be that unusual for the Northern region of the country, but apparently it affects other, warmer areas as well.
I read on a weather site that this colder trend comes from Siberia where they have up to 10-15 degrees offset from the "normal" minus temperatures (-40-45C at night) . This cold weather has affected Balkans, Poland, Germany, and is going to hit Britain and France soon (if not already).