Jesus told about frightening things that will happen before he returns.

Luke 21:25-28

25 “There will also be strange things that will happen to the sun, the moon, and the stars. In many nations, people will be very frightened, and they will be anxious when they hear the ocean roaring and see huge waves. 26 People will faint because they will be afraid as they wait for what will happen. They will be afraid because the powerful objects in the sky will be shaken {shake}. 27 Then they will see me, the one who came from heaven, coming in a cloud powerfully and very gloriously. 28 So when these things that I have just now described begin to happen, stand up straight and be brave, because it will be close to the time when God will free you from all suffering.”