Local cooling rules vary by city
A small but growing number of California local governments have started to address extreme indoor heat, and some may require cooling or set a maximum indoor temperature — but there is no statewide rule, and requirements vary by city.
Because state habitability law does not require AC, any cooling requirement usually comes from local ordinances, which differ from place to place and are changing as extreme heat becomes a bigger concern. Some areas focus on maximum indoor temperatures, and others on making sure units can be kept safe during heat.
Whether your city has such a rule takes checking local law, since these ordinances are relatively new and not universal. If you think a local cooling requirement may apply to your rental, a free review can help you understand what your landlord owes you.
This is general information about California tenant rights, not legal advice. Every situation is different.