Do books have a season?

If you visit here often - there are some of you out there I think - you'll have noticed that To Siberia has been in the 'currently reading' list on the left hand panel for about 8 or 9 months. It isn't a difficult book, but I find that I can only read it in small sections, and then put it down for a while, and leave it for sometime. I had this with another of Per Petterson's novels - Out Stealing Horses - and I have a friend who said it was a 'winter book'. I struggled to get into it in the summer months, even though a fair amount of the narrative was set in woodland during the summer, so I put it down and began it again last winter, and finished it in a few days. I began To Siberia a few weeks later, but still have it on the go - I thought it might be another 'winter book' but it seems I was wrong, and haven't yet found the right season for it. Do you think books have a season? I can't decide...