J.D. Winters writes the Destiny Bay Mystery series which started in 2014 and is set in California. It features Hawaiian girl Mele Keahi who moves from Los Angeles to Destiny Bay, CA after she loses her job and her boyfriend. Mele and her aunt can see ghosts who help Mele solve crimes.
Note: These books are a little bit short but they're not very expensive on Amazon.
Books in this series: