Typically a winter daytime temperature will be around 5C but colder conditions and snow sometimes occur. The mild winter temperature is what allows the grass to keep its healthy green colour, blanketing the countryside.
This scene reminded me of another castle, more famous, from my own County Antrim which I also photographed with a cow in front: https://panoramicireland.com/photo-tours-blog/cow-in-front-of-dunluce-castle-causeway-coast-antrim-northern-ireland