Um, I read this in October of 2006.
Dixie Storms by Barbara Hall
Meh. So, it's the end of a summer with no rain, and the oppressive heat is used as an obvious metaphor for the tension in the Peyton household. Dutch is 14, not coping with the divorce of her brother and her city cousin Norma is in town, ruining everything.
Realistically, Dutch alternates well between hating/resenting Norma and wanting to be just like her.
There's some boy drama thrown in.
Overall, I didn't really like any of the characters, so I really didn't care what happened to them. They all annoyed me.