Matthew 16:1-4   
    And the Pharisees and Sadducees came, and to test him they asked him to show them a sign from heaven.  [2] He answered them, “When it is evening, you say, ‘It will be fair weather, for the sky is red.’  [3] And in the morning, ‘It will be stormy today, for the sky is red and threatening.’ You know how to interpret the appearance of the sky, but you cannot interpret the signs of the times.  [4] An evil and adulterous generation seeks for a sign, but no sign will be given to it except the sign of Jonah.” So he left them and departed. 
Jesus considers it a culpable thing not to recognize the signs of the times. In the context of the passage he is responding to the Pharisees’ request for a sign. They do not believe He is the Messiah and if they give the impression that if they could get the sign maybe they would believe. Jesus’ response amounts to saying that they are getting plenty of signs but they do not recognize them. In other words, He has given them plenty of signs to prove what they want proven. They just fail to recognize them. They can tell the signs of the coming weather but they do not recognize the signs that Jesus is giving them. Why should He produce more?
The thing created does not dictate to the Creator. We say we will serve God IF … . That is wicked and adulterous. We do not set conditions on the Almighty. He knows what is best and He has given all that is necessary for us to rise and follow. We do not need more evidence. We do not need to set out fleeces. And we really don’t need codes or prophecy conferences or TV preachers with secret insights into the timing  of the Lord’s return who always seem to say that it is going to be in this generation.  We really don’t need that. We do not need visions and miracles and signs from heaven, although if God should choose to use such things then we welcome them. But they are not necessary beyond what we already have everyday in very ordinary manner.
He has already given us everything we need for life and godliness (II Peter 1:3). And what He has given us is the forgiveness of sins, a right standing with God, the Holy Spirit to indwell, empower, gift and convict. He has given us the Scriptures – a more sure word than any vision or voice the prophets had and even a greater testimony than what Peter, James and John had when Jesus was transfigured and spoke with Moses and Elijah (II Peter 1:16-20). We even have better than what Moses and the children of Israel had when God encountered them in the wilderness (II Corinthians 3:7-18). And we have Jesus Christ, risen from the dead, ascended to heaven and sitting at the right hand of God living in order to intercede for us (Hebrews 7:23-25) and reigning over all the created order for our sakes (Ephesians 1:20-23). We have the Table of Christ as our perpetual reminder of Jesus’ death for us until He come, the spiritual presence of Christ for our strengthening as we come by faith to the Table (I Corinthians 10:16-17). He has given us each other, the church, to worship (John 4:24), to unitedly (Ephesians 4:1-3) be a force for witness (Acts 1:8), for encouragement (Hebrews 3:12-13), for spiritual growth (Ephesians 4:11-16), and for power (Ephesians 6:10-18)  in the world.  
No, it is not more proof or evidence we need. And to ask for it is to testify just how much like the Pharisees we are.  We simply need to see just how much God has already given us, recognize that He has left nothing out and put it to work in the manner in which He directs.