Thailand expands royal rainmaking program
The Royal Rainmaking and Agricultural Aviation Department is intensifying its operations to combat drought and reduce its impact on Thailand’s agriculture. Officials have reassured the public that rainwater produced through artificial rain, or “royal rainmaking,” is of comparable quality to natural rainfall and entirely safe for consumption and farming.
On September 7, department Director-General Rachen Silparaya confirmed that Thailand is the global leader in weather modification, ranking first worldwide in rainmaking techniques. Although many countries have expressed interest in adopting Thailand’s expertise, widespread application remains limited due to the complex technical requirements and the need for favourable weather, humidity and cloud conditions.
How royal rainmaking works
Each standard rainmaking mission involves three aircraft. The first flight “disturbs” clouds, the second “feeds” them to boost density, and the third “targets” them to produce rain. When only one aircraft is available, the steps must be flown in sequence, reducing the chances of success compared to simultaneous three-plane operations.
Every flight carries at least seven crew members: two pilots, one scientist, two chemical handlers and two operators who deploy the rainmaking agents. Materials include sea salt, sodium chloride, calcium compounds, urea, dry ice and silver iodide. Disturbing clouds uses ordinary table salt, considered harmless to the environment. Feeding clouds relies on calcium chloride and calcium oxide, while targeting employs salt, urea, dry ice and very small amounts of silver iodide, which disperse widely in the atmosphere and pose minimal environmental risk.
Mr Rachen stressed that extensive testing has confirmed the safety of artificial rainwater. Analyses show that it meets World Health Organization (WHO) standards for drinking water, Food and Agriculture Organization (FAO) standards for agriculture, and all relevant Thai regulations. “Artificial rainwater is safe to drink and can be used in all typical ways without risk to humans, animals or plants,” he said. “The substances are natural and applied in very small amounts, ensuring no environmental or biological hazard.”
Expanding operations across Thailand
Between February 23 and August 26, 2025, the department carried out 2,065 flights over 161 operational days. Crews used more than 1,635 tonnes of rainmaking agents and 965 flares, achieving rainfall success in 95.65% of missions. The program benefited 141.94 million rai of farmland across 63 provinces, easing drought pressures on farmers nationwide.
To further improve efficiency, the department is building five dry ice production facilities in Tak, Phitsanulok, Khon Kaen, Buriram and Phetchaburi. With a combined output of one tonne per hour, the plants are expected to be operational in early October, reducing dependence on supplies donated by PTT Public Company Limited.
Looking to future methods
Officials are also studying the potential of weather modification rockets, which are already used in China. Rockets are cheaper and can be launched in difficult terrain, but they lack the precision of aircraft-based methods. Given Thailand’s complex geography and proximity to neighbouring countries, further development will be needed before such rockets can be deployed safely.
Mr Rachen concluded that while rockets may one day complement existing operations, they will not replace traditional aircraft missions. “Safety and effectiveness remain paramount,” he said, reaffirming the department’s commitment to protecting Thailand’s agriculture and rural communities against drought.