Why no heat breaks the habitability standard
Yes. No heat is a habitability violation in California when the landlord fails to fix it, because state law requires rentals to have working heating facilities. A home you cannot adequately heat is not considered fit to live in.
California's habitability standard (Civil Code Section 1941.1) lists heating facilities in good working order among the basics every rental must have. A broken furnace or heater — especially one left unrepaired after you report it — can breach the implied warranty of habitability, the promise that your home will be fit to live in.
The problem is more serious in cold weather and for households with children, older adults, or medical needs. What usually matters is how long the outage lasts and whether the landlord responded after being notified. If you have been left without heat and your landlord will not act, a free, confidential review can explain your options.
This is general information about California tenant rights, not legal advice. Every situation is different.