Midrash su II Re 7:6

At that very moment the wicked Pharaoh cried out: Entreat the Lord … and I will let them go (Exod. 9:28). Moses replied: You said that at the time of the first plague, and I pleaded in your behalf, but yet you did not send them away. Why should I entreat for thee and for thy servants? (ibid. 8:5). Pharaoh replied: I have sinned before the Lord your God and against you, but now I will let them go. When Moses heard that, Moses went out of the city from Pharaoh, and spread forth his hands unto the Lord; and the thunders and the hail ceased, and the rain was not poured upon the earth (ibid. 9:33). They were suspended in mid-air. When did they descend? Some descended upon the Amorites in the days of Joshua, as it is said: The Lord cast down great stones from heaven upon them (Josh. 10:11), and the remainder will fall on Gog and Magog in the days of the Messiah. And the thunders ceased (Exod. 9:34). They, too, were suspended (in mid-air). They descended in the days of Elisha, against the camp of the Arameans, as it is said: For the Lord had made the hosts of the Arameans, to hear a noise of chariots, and a noise of horses (II Kings 7:6).