Reddit mentions of The Dark is Rising (The Dark is Rising Sequence)

Yes, it's definitely The Dark Is Rising - so, so good. The rest of the books in the series are pretty fab as well - taught me everything I know about Arthurian legend.

Could it be The Dark is Rising, by Susan Cooper? There are five books in the series, all of them are excellent.

How good do you want them to be? These aren't highbrow by any means, but they are some of my favorites:

• Firestorm by David Klass
  
  
• An Abundance of Katherines by John Green or pretty much anything by John Green because he is amazing!
  
  
• The Dark is Rising Series by Susan Cooper although to be fair, I read these when I was like 12, so they might not be as good as I remember.
  
  That's all I can remember offhand. I'll think on it and add more if I have a chance.