The day of the Lord mentioned in the above verse is "a day of wrath...a day of anguish and distress, a day of destruction and desolation, a day of darkness and gloom, a day of thick black clouds" (Zep 1:14-15), the final Judgment Day. It is "a day of wrath" (Zep 1:14), the pouring out of God's blazing wrath which is spoken of more than two hundred times in the Old Testament.
There is still "time...to put an end to wrath before" it is too late. We can continue the prophet Elijah's ministry of turning away God's wrath by turning people to God and away from sin. Like Elijah, we can work to heal and restore families, especially by helping fathers to turn their hearts to their children (Sir 48:10). We can spread God's word in prophecy and teaching. Those to whom we speak may even repent, like the wicked Ninevites, and cry out: "Who knows, God may relent and forgive, and withhold his blazing wrath, so that we shall not perish" (Jon 3:9). Whoever disobeys Jesus must endure the wrath of God (Jn 3:36). We can put an end to wrath by leading people to obedient faith (Rm 1:5).
We can intercede and pray, as Elijah did. "Elijah was only a man like us, yet he prayed earnestly" and his prayers were heeded (Jas 5:17-18). "The fervent petition of a holy man is powerful indeed" (Jas 5:16). Interceding for others, we ask God for them: "In Your wrath remember compassion!" (Hab 3:2) Our love for them can cover a multitude of sins (1 Pt 4:8) and draw them to Jesus. Then they will hear the Lord say: "I will heal their defection, I will love them freely; for my wrath is turned away from them" (Hos 14:5).