The California driver's handbook states that visitors over 18 years old with a valid driver license from their home state or country may drive in California without getting a driver license as long as their home state license remains valid.

A valid Mexican driver's license may allow you to drive within the California but usually insurance companies within the CA (and the rest of the US) will require you to obtain a valid US license within a short period of time of starting up an auto insurance policy (typically 30 days) in order to keep it valid.

So while it is possible to obtain a car insurance policy with your Mexican driver's license, you will need to acquire a State license, to keep the insurance in force. If you will only be in the US for a short period of time and do not plan on acquiring a US license then you may need to see if your Mexican insurance provider will cover you while in the United States.

If you do want to get insurance and will be obtaining a State license shortly, then follow this link for a car insurance quote