'The Brewing Storm' by Paul Ruditis

Earth, air, fire, water--
A child must bring them all together.
Calm the shaking, quell the slaughter
Tonight's the night -- it's now or never.

Despite wacky weather threatening the San Francisco area, life for the Charmed Ones is as normal as ever. Normal, that is, until eleven-year-old Tyler Michaels shows up at their door. Tyler, a Firestarter, is on the run from demons, a glance at the Book of Shadows turns up new, unexpected information about the boy... and the forces for which his magic can be harnessed.

Once a century the planets align in such a way that the tides shift and the climate changes, causing unpredictable weather and earthquakes. With the world out of balance the Firestarter is charged with gathering the others Elementals on the Night of Aeolus to perform a sacred ritual. Without this ritual the weather will eventually tear the world apart. But the demons chasing Tyler want to divert the Elemental power and channel it for dark evil. The Charmed Ones must prevent this from happening at all cost--but the Night of Aeolus is already upon them...

Published by: Simon & Schuster New York

Notes:
*Featuring Piper, Phoebe, Paige, Leo, Darryl, Elise and Sheila