There was a group of kids who all had affinities for different elements or items or forces of nature, but often the affinity manifested in very subtle ways. One girl (who wore glasses, I believe) could feel/control storms; another girl was really good at metalworking/goldsmithing (I vividly recall a scene with her where she's pulling gold wire; she becomes the blacksmith's apprentice). There may have been a boy who had an affinity for plants, as well.

The setting was a town or village near a beach or port, and I seem to remember the kids going into a cave at least once. It all seemed set in the past in terms of clothing styles and how they lived, but at the same time it wasn't our world.

This next part is shakier in terms of whether it's real or not: The kids, or at least some of them, lived in some sort of academy or similar abbey-type place with lots of other people, and at least one of them had traveled a ways to be there. I no longer remember why, or what the purpose of that place was.

There were around four or five books in the series, each one focusing on a different kid. There were a few in my middle school library, which is where I read them, but I haven't heard of or seen any of them since. If you want more details, ask in the comments and I'll see what my memories can dredge up.