Although it's often available year-round, cheese truly is a seasonal product. Cheeses made in winter can have very different taste, not to mention fat content, than those produced in the summer months. 

The change in diet is one major reason why milk undergoes compositional changes with the seasons. In the case of our herd, the biggest change that we see is in the ratio of solids (fats and proteins) in the milk, which become higher in winter.

Read More Here

Photo by Barry Staver, via Doing Time Together, Winter 2012