For the last fifty years, China has maintained something of a secret weapon; the Weather Modification Department (WMD). This outfit currently has 30,000 personnel (most of them civilian part-timers) and belongs to the Chinese Air Force. The WMD operates useful items, like fog dispersal equipment (to keep air strips open in bad weather), and aircraft (or rocket launchers) that can deliver silver iodide or dry ice into clouds to induce rainfall. Putting too much silver iodide into clouds will delay the rain.
WMD personnel admit that their capabilities are not a hundred percent reliable, and that they do not have the resources to modify weather over a large area. There is also a general lack of evidence that the WMD can actually deliver useful results in a combat situation. But the WMD does have half a century of experience. That, and the current size of the WMD, is something few other nations can match.