OK, in southern California you're going to need to design for heat. Here's my article about it: https://www.backyardchickens.com/articles/hot-climate-chicken-housing-and-care.77263/
If you're not already planning on an Open Air coop, I strongly suggest that design.
Open Air Coops
https://www.backyardchickens.com/articles/jens-hens-a-southern-texas-coop.75707/
https://www.backyardchickens.com/articles/my-positive-local-action-coop.72804/
https://www.backyardchickens.com/articles/california-living.68130/
If you're not already planning on an Open Air coop, I strongly suggest that design.
Open Air Coops
https://www.backyardchickens.com/articles/jens-hens-a-southern-texas-coop.75707/
https://www.backyardchickens.com/articles/my-positive-local-action-coop.72804/
https://www.backyardchickens.com/articles/california-living.68130/