Dreams, visions, prophecies, and other signs were associated with the coming of the Holy Spirit just as had been foretold by the prophet Joel.
Details in Joel's prophecy also revealed signs that will surround Christ's second coming to earth that are yet to be fulfilled. Even the prophets through whom this information was revealed did not always fully understand the extent of the revelation given to them. Their understanding was limited by the fact that the revelation God gave them did not include every detail concerning the events they foretold. Nonetheless, what God has revealed has happened, and will continue to happen, exactly as He has said.
The prophecies of God can best be understood and accurately anticipated by a normal reading of the Scriptures when taken in their literal, grammatical, and historical context.