know enough to come in out of the rain
To have enough common sense to choose an obvious solution (like going inside if it starts raining). I'm not surprised his latest business venture failed too—that fool doesn't know enough to come in out of the rain.
come in out of the rain, know enough to
Show common sense. Alluding to having enough sense to seek shelter, this hyperbolic phrase is often used in the negative, as in Peter doesn't know enough to come in out of the rain. [Late 1800s]