We have observed since the water crisis began in South Africa that many Muslims under the rule and command of the Ulama congregate after the Fardh Sal

Question

We have observed since the water crisis began in South Africa that many Muslims under the rule and command of the Ulama congregate after the Fardh Salaat to recite Surah Yaaseen so that Allah Ta'ala sends rains. A loud dua is then made by the Imaam Is this a valid Shar'i practice?