'Darkness' in the Bible

For, behold, he who forms the mountains, and creates the wind, and declares to man what is his thought; who makes the morning darkness, and treads on the high places of the Earth: Yahweh, the God of Armies, is his name."

"Woe to you who desire the day of Yahweh! Why do you long for the day of Yahweh? It is darkness, and not light.

Won't the day of Yahweh be darkness, and not light? Even very dark, and no brightness in it?