Revelation 11:6

These [two witnesses] have power to shut up the sky, so that no rain may fall during the days of their prophesying (their prediction of events relating to Christ's kingdom and its speedy triumph); and they also have power to turn the waters into blood and to smite and scourge the earth with all manner of plagues as often as they choose. [Exod. 7:17, 19; I Kings 17:1.]