Kestrel (don't call her Susan) Murphy is angry. Forced to leave her posh San Francisco Bay Area home by her father's illness, she's living in Jurupa (sounds like vomiting), Southern California. It's too hot. The people are stupid. And you have to chew the air to get the oxygen out of it. On the plus side, Kestrel is a witch. Well, a witch-in-training. And she's going acquire the magic she needs to get her life back to normal. At first, she barely notices the people around her-Aunt Ariel, who's taken her in and is herself a well-known white witch; Jose Iturrigaray, the quiet, talented young artist; Blake Cump, troublemaker extraordinaire; Laura Greenwood, who wants to be Kestrel's friend. But life has its own magic, and gradually Kestrel finds that much of one's success as a witch lies in being open to it.
(taken from goodreads.com)
I saw the trailer for this one and decided it looked like a book I'd really enjoy. Here's the trailer, if you're interested.