Luke 21

And He said: “Take heed that you not be deceived. For many will come in My name, saying, ‘I am He,’ and, ‘The time has drawn near.’ Therefore do not go after them. But when you hear of wars and commotions, do not be terrified; for these things must come to pass first, but the end will not come immediately.  Then He said to them, “Nation will rise against nation, and kingdom against kingdom.  And there will be great earthquakes in various places, and famines and pestilences; and there will be fearful sights and great signs from heaven. ” vv.8-11

Read chapter 21
Signs that the Lord is speaking of this chapter can be confusing if you try to fit it in to a time that is not what Jesus is talking about.  One view is that the this time is now with many claiming that they are God or with the increase of wars and commotions we see all around the world or all the natural disasters like earthquakes, famines and pestilences happening today.   Another view is that this is talking of a even future time at the end of the Kingdom, before the thousand years (Revelation 20).  The idea is that the Lord is talking to the disciples here as if they are to experience this.  They are no longer alive today so the only way for them to be present would be after the resurrection when they are raised from the dead.  Also, Jesus says when you hear of wars, not just an increase of wars.  There have been wars constantly and continuously since Jesus spoke these words and every generation believes their time is when this will take place yet the world continues in the fallen state.  Moreover, a time of perfect peace when there are absolutely no wars or earthquakes or other disasters that when they do come it will surely be an astounding and scary thing than just the norm as it is today.  
Considering these views will cause you to think and study more on the timeline of events to come.  It's way more than just "heaven's next" as ignorant people like to think.  Take a look and see what you'll find.