There were some Pharisees and Sadducees come to Jesus to trap him. They ask Him to make miracles to prove that he came from God.
Jesus said, you can predict the weather by looking at the sky condition, but signs of the times you can not predict!
A wicked and morally unfaithful generation craves a sign, but no sign shall be given to it except the sign of the prophet Jonah. Then He left them and went away.