Upvote:4
Your citizenship is not relevant; what matters is whether you are a resident of California. Adult nonresidents temporarily in California can drive with their foreign or out-of-state driver's license (from their place of residence) without limit.
Visitors over 18 years old with a valid DL from their home state or country may drive in California without getting a California DL as long as their home state or country DL is valid.
However, residents of California can drive with a foreign or out-of-state driver's license for no more than 10 days after becoming a resident of California.
When you become a California resident and you want to drive in California, you must apply for a California DL within 10 days.