There are many reasons why a cat might meow incessantly all day long. It could be due to being frightened, stressed, or in heat. Generally, cats may meow incessantly when they are in a new environment or encounter strangers. Owners should comfort their cats promptly to make them feel safe.

It could also be that your cat is in heat. Cats will meow incessantly when they are in heat, which is a very normal phenomenon. You can check your cat's age. If it is of heat age, then you don't need to worry too much. You can improve the situation by breeding it. Once the cat gets what it needs, the incessant meowing will gradually stop.