Really? No compelling state interest? People are performing a painful and unnecessary surgical procedure on infants, without their consent, affecting them for the rest of their lives, for superstitious and aesthetic (i.e. self-centered) reasons. The state always has an interest in protecting children from abuse. That will be the argument, and I’m not sure I disagree with it.
That said, I wouldn’t support a ban like this. It should be a family decision. But I really don’t think non-Jewish parents (for instance) should consider it the “default” (the “health reasons” are bullshit in a first world country), or that a father should decide to circumcise just because he was.
But even if the State of California decided it had a compelling interest that it could defend -- very unlikely in this case because no public interest is involved -- it's very difficult to imagine ANY municipality that could justify it. Municipal authorities in most jurisdictions do not have a grant of this kind of authority: in this case it's not so much the compelling that's pertinent as it is the interest itself. An authority that runs parks and appoints dog catchers isn't competent (in both the original and modern sense) to make such determinations. By its past actions, clearly San Francisco has demonstrated it is not.
Thank God I don't live in California anymore, or in a state where they think this is the government's business.