The question you pose is probably as vague as your understand it to mean from the employer's mouth. On its face, this appears lawful as fitting "company culture" is not a protected class unless "company culture" is a protected class like race, religion, gender, etc.
You may want to inquire as to the specifics of what "company culture" means.
(I am not licensed to practice in CA so there may be a protected class unique to CA that I am unaware of).
CA is an at-will employment state. That means you can be fired for any reason or no reason, just not an illegal discriminatory reason. Not fitting into company culture could have many meanings. If it means you were fired because of your race, age, nationality, religion, sex or other protected category you might have a claim. If it is because you wear suits and everyone else wears jeans, no case.
The response given is not intended to create, nor does it create an ongoing duty to respond to questions. The response does not form an attorney-client relationship, nor is it intended to be anything other than the educated opinion of the author. It should not be relied upon as legal advice. The response given is based upon the limited facts provided by the person asking the question. To the extent additional or different facts exist, the response might possibly change. Attorney is licensed to practice law only in the State of California. Responses are based solely on California law unless stated otherwise.
You are likely employed at will which means that you can be terminated without notice and without cause as long as the termination is not for an unlawful reason.
A termination may be wrongful if:
An employee has a written employment contract that is violated by the termination.
An employee can show that the parties agreed by words or conduct that the employee would only be discharged for good cause.
The termination was somehow related to an employee’s age, disability, family or marital status, national origin, pregnancy, race, religion, sex or sexual orientation.
The termination was an act of retaliation against an employee who has filed a complaint about sexual harassment, a wage and hour claim or any other similar employment matter
The termination was an act of retaliation against an employee who discovers that their employer is breaking the law and reports them to the authorities — “blows the whistle.”
If you think that the employer fired you for an unlawful reason and your failure to fit into the company culture was a pretext, than you may have a claim.