A day of darkness and of gloominess, a day of clouds and of thick darkness, as the morning spread upon the mountains: a great people and a strong; there hath not been ever the like, neither shall be any more after it, even to the years of many generations.
Joel 2:1 Blow ye the trumpet in Zion, and sound an alarm in my holy mountain: let all the inhabitants of the land tremble: for the day of the LORD cometh, for it is nigh at hand;
Joel 2:2 A day of darkness and of gloominess, a day of clouds and of thick darkness, as the morning spread upon the mountains: a great people and a strong; there hath not been ever the like, neither shall be any more after it, even to the years of many generations.
Joel 2:3 A fire devoureth before them; and behind them a flame burneth: the land is as the garden of Eden before them, and behind them a desolate wilderness; yea, and nothing shall escape them.
Joel 2:4 The appearance of them is as the appearance of horses; and as horsemen, so shall they run.
The verse centers on "darkness", "gloominess", "clouds", "thick", "morning", "spread", and "upon". It is saying that the verse draws attention to "darkness" and "gloominess", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 1's "Blow ye the trumpet in Zion and..." into verse 3's "A fire devoureth before them and behind...", so "darkness" and "gloominess" belong inside that flow. In Joel context, the local focus is covenant, worship, and faithfulness.
A plain takeaway is to answer the verse's own emphasis on "darkness" and "gloominess" with trust shaped by these words, not by a vague optimism outside the passage.