Nothing is more boring than a blue sky. The blue color is nice, sure, but it’s so samey. For really interesting skies, you want clouds.
Clouds provide drama. They give your scene interest from top to bottom. They are beautiful and compelling. And overcast days give you ample opportunity to include them, particularly during those magic hours.
Sunrise and sunset are the best times for including dramatic skies–the light just behind those clouds creates skyscapes with beautiful colors and rich texture. If you’re out on a cloudy day, make sure you stick around until sunset to take full advantage of those beautiful cloudy day skies.