State of CA's Health and Human Services Agency & California Department of Public Health have announced a travel advisory.
1. Persons arriving in California from other states or countries, including returning California residents, should practice self-quarantine for 14 days after arrival. These persons should limit their interactions to their immediate household. This recommendation does not apply to individuals who cross state or country borders for essential travel. 
2. Californians are encouraged to stay home or in their region and avoid non-essential travel to other states or countries. Avoiding travel can reduce the risk of virus transmission and bringing the virus back to California.
 “Non-essential travel” includes travel that is considered tourism or recreational in nature.
 “Essential travel” includes: work and study, critical infrastructure support, economic services and supply chains, health, immediate medical care, and safety and security.