'Anger' in the Bible

Who can tell if God will turn and repent, and turn away from his fierce anger, that we perish not?

And he prayed unto the LORD, and said, I pray thee, O LORD, was not this my saying, when I was yet in my country? Therefore I fled before unto Tarshish: for I knew that thou art a gracious God, and merciful, slow to anger, and of great kindness, and repentest thee of the evil.

Then God asked Jonah, "Is your anger about the vine plant justified?" And he answered, "Absolutely! I'm so angry I could die!"