In Old Testament times, God rose up prophets to tell of coming calamity. Today, He offers warning of impending judgment through the Scriptures (we can know the season, not the precise time) of certain signs and events, and through the words of the watchmen that He establishes; spiritually sensitive people tasked with understanding and relaying Bible prophecy.
Be warned, not all who claim to be watchmen, are. Ego and monetary gain has put more people into the prophecy field than God has. In TV pulpits too, for that matter.
A couple of more things about judgment. It comes swiftly and unexpectedly. Most people don’t heed the warning signs (they’re oblivious) and are taken unaware. The deceived and wicked have no discernment.
“And for this cause God shall send them strong delusion, that they should believe a lie: That they all might be damned who believed not the truth, but had pleasure in unrighteousness” (2 Thessalonians 2:11-12).