Cesky Krumlov on December 25

I am no expert on Cesky Krumlov but I will base my answer on what happens in Prague.
The Czech celebrate their main Christmas meal on the evening of the 24th and things generally close around midday or early afternoon that day. On Christmas day itself many places do open but usually not till at least 12.00 noon and the main tourist places and tourist shops open around then,the more local places shops/bars are likely to remain closed .
I don't know if this will apply to Cesky Krumlov but hopefully it will.
Might be worth emailing the local Tourist office for information if no one else can add to what I have said.

Hi hishieny. A word of caution - CK is a wonderful, bustling area in summer, but it is largely geared toward outdoor activities, and in December, the average temp will be around 35 degrees F. I wouldn't find it appealing to go then, and I'm guessing it is mostly closed in winter. Enjoy your trip!

Was there Dec. 26-27 last year & pretty much everything was open: shops, cozy restaurants, etc. There was a Christmas Market in the center. The Castle was not open.

Ive spent two Christmases in CK and its well worth going. Not much of a crowd, but most everything was open except for a few shops here and there that were closed. Yes, the castle itself is closed, but the castle grounds, courtyards, and gardens were open to explore. A VERY small Christmas market is in the small town square. At night when the daytrip tourists leave, the bars are lively with locals. I was lucky with great weather two years in a row--sunny and in the low 50s F. Local brewery down there too! Im talking to YOU Gus! Eggenberg or something like that, if I recall. :)

I will get there some time Frank, but have started my own brewing. My mate in Prague and I have experimented with making some cider,only 20 litres at the moment and as of yesterday the fermentation has finished and we are waiting for it to mature a bit before being drunk ,hoping for 7-8% alcohol. I won,t be back in Prague till April so he better keep me some.
There is a new Micro brewery In Prague (Narodni Pivovar) near the National theatre and I can highly recommend it for both beer and food was in twice a few weeks ago.

Thanks for the tip Gus. I'll try to check it out when I'm there in a few weeks.