Building a record of the outage
You prove a no-heat problem with documentation: written reports to your landlord, dated notes or a log of when the heat was out, indoor temperature readings, any repair records, and short videos showing a thermostat or thermometer.
Because a lack of heat is not always obvious in a single photo, a clear written record and temperature readings matter most. Photograph a thermometer or thermostat showing the cold indoor temperature, with the date visible. Save every text and email with your landlord, since these show what the landlord knew and when.
Keep a simple log of the dates and times you had no heat, note the outside weather if it was cold, and hold on to any repair invoices. You do not need an expert to prove it; a consistent, dated record usually tells the story. A free review can help you understand which evidence matters most in your situation.
This is general information about California tenant rights, not legal advice. Every situation is different.