For anywhere along the west coast, the Sunset Western Garden book is a much better indicator of plant suitability than is just the USDA hardiness zone. All that measures is winter cold - it does not take into consideration any of the many other factors that influence plant performance, like altitude, topography, marine influences, summer heat and humidity, winds, rainfall, etc.

According to the Sunset book, you are located in Sunset zone 22-24 depending on how close to the coast you are. And unfortunately, virtually NO flowering cherry varieties - including Yoshino - are recommended for Sunset zones higher than 20, That eliminates all of SoCal except for a few high desert locations.

ETA: If you are anywhere south of Santa Barbara, you are at least a USDA zone 10

Gardengal48, Thank you for the extremely helpful info! I am located more inland than the directly on the coast (around A 30-40 minute drive) but still get coastal fog that burns off after a few hours. I just purchased the book from a bookshop, and it says im in a zone 18. Do you think their is a better variety for me choose? or just avoid it all together?

A Sunset zone 18 IS pretty far inland! You might be able to get away with it but there are much better spring flowering trees for your locale than an ornamental cherry.