Did God change from a wrathful God to a loving God between Old Testament and New Testament?

This question is mainly to the evangelical Christians and Bible believing Christians, who believe that God doesn't change and His nature is Love. The Old Testament is filled with accounts that describe how God poured out His wrath on people, including His chosen people, the Israelites. However, when we read the New Testament particularly the life, teachings and message of the Lord Jesus Christ we don't see the outpouring of God's wrath on people. Instead, we read about God's grace, mercy, and love. How do we square these two seemingly opposite manifestations of God's nature?