According to God’s promise, we await new heavens and a new earth. In his farewell message in a letter that is largely apocalyptic, Peter exhorts his readers to be ready at all times so as to be found spotless and unblemished when the Day of the Lord, a day which has been promised them and for which they eagerly await, finally arrives. In the apocalyptic language of the letter, Peter graphically paints to his readers what the Day of the Lord will be like: ‘ The heavens will be dissolved by fire, to be replaced by new heavens and a new earth.’ Peter’s immediate audience might have been familiar with the literature dealing with the end times, and as such would not have been alarmed at the way Peter depicted the Day of the Lord. As a matter of fact, they would have expected nothing less. For someone not familiar with apocalyptic language, the question would be: Why would the heavens be dissolved? 
In the Genesis account of creation, heaven and earth are created on the first day (cf. Genesis 1:1), and it is upon them that the other realities are created (cf. Genesis 1:2ff). In other words, heaven and earth acted as receptacles to God’s creation. Heaven and earth, as it were, are the foundation of the created universe. Without them, so to speak, creation would have nothing to ground them. When Peter talks about the dissolution of the heavens, therefore, he is only painting in a graphic manner the re-creation of the heavens and earth, for it is to this that the Day of the Lord boils down. God’s promise to humanity is a creation of a new heaven and earth. While the fulfillment of this promise might not necessarily come down to the graphic dissolution of the created universe (as it did during the floods at the time of Noah [cf. Genesis 6:5ff]), the outcome remains the same: the creation of a  new universe in which righteousness dwells. Righteousness becomes the distinguishing character of this new creation, and Peter does well to “warn” his readers that nothing less is expected of them. The only way to avoid the fiery destruction is  to be principled in order to be stable in their faith, which  is the knowledge of our Lord Jesus Christ.