You can have your cake and eat it
Often when you get perfectly clear skies at night and you've spent hours chasing new compositions with the stars, it means that when the sun begins to rise it's time to head home. No cloud makes for a far less interesting sunrise.
This Saturday night just passed provided awesome clear skies but as the sky began to lighten a weather front gradually moved in and by the time the sun peeped over the horizon it looked like this.
Occasionally you can have your cake and eat it.