Spending more than nine months in California during a taxable year creates a presumption that you are a California resident for income tax purposes. This presumption can be rebutted with evidence that your presence was temporary or transitory. California residency can also apply with fewer days depending on domicile, purpose of stay, and other facts and circumstances.
https://www.ftb.ca.gov/tax-pros/procedures/residency-and-sourcing-technical-manual-disclosure.pdf