Because of the increase in wickedness, the love of most will grow cold but if you stand firm to the end, you will be saved.  This gospel of the kingdom of God will be preached in the whole world as a testimony to all nations and then the end will come.  Matt 24:12-14

When you hear of wars and revolutions do not be frightened.  Nation will rise against nation and kingdom against kingdom.  There will be earthquakes, famines, diseases, terrifying events and tremendous signs from heaven.  Luke 21:9-11 

If those days were not cut short, no one would survive but for the sake of the elect those days will be shortened.  Matt 24:22

There will be great tribulation unequaled from the beginning of the world until now and never to be equaled again.  Matt 24:21

The sun will be darkened and the moon will not give its light.  The stars will fall from the sky and the heavenly bodies will be shaken.  At that time, my sign will appear in the sky and all the nations of the earth will mourn.  Matt 24:29-30

You will see me sitting at the right hand of the Mighty One and coming on the clouds of heaven...  Matt 26:64

…with power and great glory.  I will send my angels with a loud trumpet call and they will gather my elect from the four winds - from one end of the heavens to the other.  Matt 24:30-31

As lightning that comes from the east is visible even in the west, so will it be at my return. 
Matt 24:27 

No one knows about that day - not even the angels in heaven but only my Father.  Matt 24:36

Keep watch, you do not know on what day your Lord will come.  Matt 24:42

You must be ready because I will come at an hour when you do not expect me.  Matt 24:44

Be careful or your heart will be overloaded with the indulgences, diversions and anxieties of life and that day will close on you unexpectedly like a trap.  It will come upon all those who live on the face of the whole earth.  Be always on the watch and pray that you are worthy to escape all that is about to happen so you may be able to stand before me.  Luke 21:34-36