Beeping sound coming from engine when turned off, but no warning lights?

What is your question?

In cold weather after driving and the car is turned off, a beeping noise starts from inside the engine. I cannot hear the beeping when inside the car, but is clearly heard when standing outside with the hood up. I have no dash display warnings. It is a consistent sounding beep and not overly loud, and no warning lights on. Any cause for concern?