Both written by Jenny Han, The Summer I Turned Pretty and It's Not Summer Without You are flying around my classroom these days. I must admit I have not read them yet (but I did just download the first book on my iPod), but my students say the books have realistic characters and suspenseful, heartbreaking plots.

Here's what the author's website says about the first book The Summer I Turned Pretty:
Belly measures her life in summers. Everything good, everything magical happens between the months of June and August. Winters are simply a time to count the weeks until the next summer, a place away from the beach house, away from Susannah, and most importantly, away from Jeremiah and Conrad. They are the boys that Belly has known since her very first summer--they have been her brother figures, her crushes, and everything in between. But one summer, one terrible and wonderful summer, the more everything changes, the more it all ends up just the way it should have been all along.
For more information about these books, click here to go to the author's site.
Pick up the book, give it a try, and let me know what you think.
Think summer, keep reading!
-stenson
*The photo is taken from the author's website too!