I haven't been to Vienna in winter but I just completed a 4 night trip during the 2nd week of December. 2 days were mild-ish but fairly clear and 2 days of mostly rain. However, the Christmas markets were wonderful and despite the rain it's an easy city to discover on foot. Very nice dining opportunities around the city as well.

We definitely plan on visiting again during spring or summer to experience the city in a different season.

Stayed at the Hilton Vienna Plaza which was centrally located and well positioned to visit the various Christmas markets. I think it was around 10-15mins cab ride from the Hbf (main train station).