Hi Darren,
Jer 4:9 "And it shall come to pass in that day," says the LORD,
I think we can safely assume that this is talking about the day of the Lord's return, as you can also see in verse 13.
Jer 4:13 "Behold, He shall come up like clouds, And His chariots like a whirlwind. His horses are swifter than eagles. Woe to us, for we are plundered!"
In verses 22 and 23 it's talking about the condition of the people of the "earth" being totally corrupt "without form, and void," "a wilderness." Of course all this is speaking in symbolic language.
Jer 4:22 "For My people [are] foolish, They have not known Me. They [are] silly children, And they have no understanding. They [are] wise to do evil, But to do good they have no knowledge."
v. 23 I beheld the earth, and indeed [it was] without form, and void; And the heavens, they [had] no light.
Jer 4:26 I beheld, and indeed the fruitful land [was] a wilderness...
And this is the warning of what will happen at His return to judge the earth.
v. 26 And all its cities were broken down At the presence of the LORD, By His fierce anger.
v. 27 For thus says the LORD: "The whole land shall be desolate; Yet I will not make a full end.
v. 28 For this shall the earth mourn, And the heavens above be black, Because I have spoken. I have purposed and will not relent, Nor will I turn back from it.
Hope this is helpful.
mercy, peace and love
Kat