2:28–32 The promise of abundant life and rescue from the judgment of the day of the Lord has been given out of the free grace of God (2:18–27). Joel now turns to tell of the signs that will precede the coming of the day. Thus, afterward in 2:28 refers not to events that will take place after the coming of the day, but before its imminent arrival (cf. before in v. 31).

As found also in NT tradition, the day will be preceded by both cosmic and earthly signs (cf. Mark 13:7–8, 24–25 and parallels; Luke 21:20, 25–26). Mark speaks of “wars and rumors of war” (Mark 13:7), and the blood, fire, and smoke of Joel 2:30 probably refer to the burning of cities and the slaughter of their populace. The darkening of the sun and the changing of the moon to blood in 2:31, on the other hand, are not natural…