God NEVER changes, BUT His mind seems to. 
A little more to the blog CAN WE REALLY CHANGE GOD'S MIND (Things That Make You Go Hmmm).

There are a handful of Scriptural passages that speak to God not changing.  The most well-known, at least in my mind, is Hebrews 13:8 - "Jesus Christ is the same yesterday and today and forever.
Another one is Numbers 28:19 - "God is not a man, that he should lie, nor a son of man, that he should change his mind.
In addition, Psalm 110:4 - "The LORD has sworn and will not change his mind: "You are a priest forever, in the order of Melchizedek.
The theme continues in Malachi 3:6 - "I the LORD do not change. So you, O descendants of Jacob, are not destroyed." 
The New Testament gets involved with the previously mentioned Hebrew passage and James 1:17 - "Every good and perfect gift is from above, coming down from the Father of the heavenly lights, who does not change like shifting shadows."   

BUT THEN along comes Jeremiah 18:7-10 and makes you think.  The LORD says,

"If at any time I announce that a nation or kingdom is to be uprooted, torn down and destroyed, and if that nation I warned repents of its evil, then I will relent and not inflict on it the disaster I had planned.  And if at another time I announce that a nation or kingdom is to be built up and planted, and if it does evil in my sight and does not obey me, then I will reconsider the good I had intended to do for it."    

This conditional statement of possible reconsideration leads me to believe God may be influenced to change His mind, especially, when He was the one who stated the "if...then" formula to begin with and in light of the word "reconsider".  If you observe the other verses that I have sited, you will note that the Hebrews, Malachi, and James text do not refer at all to God's mind.  The Psalm 110:4 passage is speaking to a specific decision and not to God's overall decision-making process.  Another Scripture passage to consider that is not mentioned is Genesis 18:16-33.  Here, Abraham attempts to influence the Lord's decision to destroy Sodom because his nephew Lot lives there.  This bartering or negotiating with God seems to be working until we get to the end and find out that there are not even ten righteous people in the cities.  But God is still merciful to Lot.  Numbers 28:19, however, poses an interesting ponderment.

To start off, the first part of "God is not a man, that he should lie" - "God is not a man" - is interesting because later in history God becomes man in Jesus.  The second part is interesting too, it reads "nor a son of man, that he should change his mind".  One of the titles Jesus held was Son of Man as well as Son of God.  The way in which my spirit-man interprets "nor...that he should change his mind" in this verse is nor...that He should be wishy-washy in His decisions with everything, all the time, especially us.

According to the Jeremiah passage mentioned above, I read and hear God's essence does not change, but His mind on certain matters can change.  After the last word of that verse I can see and hear God tacking on - I have the right and reserve the right to change my mind - for my decisions are righteous in justice and schedule - perfect in fairness and timing.

So, is God the same yesterday, today, and forever?  His nature is.  He may change His mind, but it will always be in line with His nature"This is the message we have heard from him and declare to you: God is light; in him there is no darkness at all." - 1 John 1:5  There is nothing that we can say or do to ever force God into any decision.  God is going to do what God is going to do.  However, it is very comforting to know that God is going to hear our (the believer's) prayer or petition because of His promise to never leave us or forsake us (Hebrews 13:5) and because of the high price He paid to be our Mediator (Hebrews 9:15).

Here's a little extra - did God know about the change of mind beforehand?  Is the Jeremiah 18:7-10 statement in the Bible and the portrayal of God as a God that can be influenced really a show, at least to God Himself?  Another "Bunny Trail" for another day.