"And it was told the house of David, saying, Syria is confederate with Ephraim. And his heart (King Ahaz's) was moved, and the heart of his people, as the trees of wood are moved with the wind." (Isaiah 7:2, emphasis mine) The previous chapter opens with the death of King Uzziah in 642 BC. What we have there is symbolism. The trees symbolizing the people and the wind symbolizing God's Spirit blowing through and exciting. The wind through the trees. It symbolizes the rush of God's presence available to do whatever He's called you for. As if, now you're ready. It happened with David over three-hundred years prior. The first book of Chronicles (14:14-16a) says "Therefore David enquired again of God; and God said unto him, Go not up after them; turn away from them, and come upon them over against the mulberry trees. And it shall be, when thou shalt hear a sound of going in the tops of the mulberry trees, that then thou shalt go out to battle: for God is gone forth before thee to smite the host of the Philistines. David therefore did as God commanded him..."
It’s called “psithurism” and it’s the sound that the leaves make when moved by the wind.
But think about this for a second. How do you know, when something symbolic happens, that it's truly a sign from God? Yes, God told David plainly what he would see—the wind through the trees—and what it meant, so when it happened, he'd know. In the passage from Isaiah, the current king Ahaz is told by God then to "Ask thee a sign of the Lord thy God" (7:11). In the next verse, Ahaz refuses, saying "I will not ask, neither will I tempt the Lord." This is one end of the spectrum: to deny any outward sign as an inferior means of communication from Him. Gideon, one of God's chosen judges (in an era before David, before Israel had a kingship) had trouble interpreting signs. His story is told in the sixth chapter of Judges. And his is the other end of the spectrum. I think that we still deal with this in many ways. There's the plain. There's the symbolic. And everything in between. This being said, there was wisdom in Ahaz's approach, but not when God plainly told him to "ask thee a sign". We're fallible. We need help. So God says to ask for help, the plainest command, and we falter. With this in mind, you can see how Gideon would be hesitant to accept something symbolic. Especially after he asked a sign to help him know "If thou wilt save Israel by mind hand, as Thou hast said." (Judges 6:36) In Ahaz's case, God overrules the doubt and proclaims the sign of Jesus. He tells him "Therefore the Lord Himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call His name Immanuel." (Isaiah 7:14, emphasis mine) Immanuel means "God with us." If God wants to give a sign, you'd better believe it.
Nothing, nothing trumps knowing Jesus as a person. What means one thing to you, might mean something altogether different (and not in a good way) to someone else. Without God, many "signs" are relative and subjective.
Jesus dealt with the superstitious element of humanity: "And the Pharisees came forth, and began to question with Him, seeking of Him a sign from Heaven, tempting Him. And He sighed deeply in His spirit, and saith, Why doth this generation seek after a sign? verily I say unto you, There shall no sign be given unto this generation." (Mark 8:11-12) The Jews of Jesus' day had become so dependent on "signs from Heaven" that Jesus got fed up and essentially condemned the whole paradigm--and, it would seem, stayed any sign from manifesting for that generation. That's pretty awesome. He tells them in John's Gospel (5:39) "Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me. " That's the answer. Any sign, however nebulous and obtuse, if it's not helping you know God—if it's not leading you to God, to Jesus, means nothing. Don't assign it any meaning. Because here's the scary part. We can take our faith and put it out there invested things that aren't of God, and receive some sort of commensurate return on our investment. But it's all lies. It's all neither here nor there. Meanings come and go, and if they're not based on God Himself and His word, they'll lead us astray. We'll be believing lies. You can be sure, then, that the Lord's power won't be there to help.
Listen for the wind through the trees. And don't do anything until you hear it. Better yet, listen for the Holy Spirit. Jesus came to give Him back to us.