Will neutering stop the yowling?

For oestrus and mating-related calling, yes, in the large majority of cases. It is also the single most effective intervention for spraying and roaming.

My neutered senior cat yowls at night. Why?

This is a recognised sign of feline cognitive dysfunction, and also of hyperthyroidism and high blood pressure. All three are common in older cats and all three are worth ruling out with a vet.

Is a caterwaul the same as a meow?

No. A caterwaul is far longer, louder and more modulated. Meows are short and directed at humans; caterwauls carry over distance and are directed at other cats.

Why do cats yowl at night?

Q: Why do cats yowl at night?

Prolonged night-time yowling in unspayed females is usually oestrus calling, which advertises availability to males and can continue for several days at a time. Unneutered males yowl in response and when competing. Neutering resolves the behaviour in the large majority of cases.

What it sounds like

Long, loud, wavering calls that rise and fall, repeated over extended periods, most often after dark.

What it means

Reproductive advertisement. It is not distress, though it sounds like it.

Using it in PurrPlay

Recognition only. If you are hearing this from your own cat, the answer is a veterinary conversation, not an app.

Common questions

Will neutering stop the yowling?: For oestrus and mating-related calling, yes, in the large majority of cases. It is also the single most effective intervention for spraying and roaming.
My neutered senior cat yowls at night. Why?: This is a recognised sign of feline cognitive dysfunction, and also of hyperthyroidism and high blood pressure. All three are common in older cats and all three are worth ruling out with a vet.
Is a caterwaul the same as a meow?: No. A caterwaul is far longer, louder and more modulated. Meows are short and directed at humans; caterwauls carry over distance and are directed at other cats.

Sources

The behavioural claims on this page trace to peer-reviewed work. Where the evidence is thin or contested, the page says so instead of citing something that does not support it.

Bradshaw, J. (2016). Sociality in cats: A comparative review. Journal of Veterinary Behavior.Reviews feline social structure and why domestic cats direct social signals at humans.
Schötz, S., van de Weijer, J., & Eklund, R. (2017). Melody matters: An acoustic study of domestic cat meows. Proceedings of Fonetik 2017.Descriptive acoustic baselines for feline vocalisation types, including pitch contour.