Cloud seeding is not only still done, it’s more active and technologically advanced than at any point in its seven-decade history. In the United States alone, 11 states run operational programs: California, Colorado, Idaho, Kansas, Nevada, New Mexico, North Dakota, Oklahoma, Texas, Utah, and Wyoming. Internationally, major programs operate in Australia, Chile, China, France, India, Israel, Saudi Arabia, Spain, and other countries.
What Modern Programs Look Like
Utah offers a good snapshot of how cloud seeding works today. The state has been seeding clouds since the early 1950s, and its current network of over 170 ground-based generators is the largest remotely operated system of its kind in the country. The entire network runs without anyone physically present at the generators, using remote controls and real-time reporting. During the 2023-2024 winter season, Utah conducted seeding during 184 storm events statewide, with aircraft handling 20 of those. Operations run from November through April, targeting mountain ranges across the state to boost winter snowpack and, ultimately, water supply.
The basic principle hasn’t changed much since the 1940s. Silver iodide particles are released into clouds, either from ground-based generators or aircraft. These particles have a crystal structure that closely mimics ice, which encourages water droplets in clouds to freeze and grow heavy enough to fall as precipitation. Temperature and humidity in the target area both influence how well this works.
How Well It Works
A U.S. Government Accountability Office review of cloud seeding studies found that estimates of additional precipitation ranged from 0 to 20 percent. That’s a wide range, and it reflects a real limitation: results depend heavily on having the right cloud conditions at the right time. You can’t squeeze rain from a clear sky. Seeding works by enhancing storms that are already forming, not by creating weather from nothing.
Despite that variability, the cost-effectiveness keeps programs running. For water-stressed western states, even a modest increase in snowpack translates into meaningful additional water flowing into reservoirs during spring melt.
China’s Massive Operation
The largest cloud seeding effort in the world belongs to China, where weather modification is institutionalized at the national level. The Chinese government treats it as a core tool for food security, water supply, and disaster prevention. Operations cover an average of 5 million square kilometers annually, more than half the country’s total area. Government targets have called for increasing rain and snowfall by more than 60 billion tons per year and expanding hail-protected areas to over 540,000 square kilometers.
China’s program goes well beyond boosting rainfall. It includes hail suppression to protect crops, fog clearance around airports and highways, and even guaranteeing clear skies for major public events. Six regional focus areas span from the northwest to the northeast, each with tailored intervention strategies covering hundreds of square kilometers.
New Technology Is Changing the Field
One of the biggest recent developments is the use of autonomous drones for seeding. Researchers have successfully demonstrated uncrewed aircraft systems equipped with weather sensors and cloud-measuring instruments that can search for suitable clouds, fly into them, release seeding material, and monitor results, all with minimal human input. Early trials in the U.S. Great Plains showed that these systems can repeatedly execute seeding maneuvers and may significantly improve targeting accuracy compared to traditional aircraft or ground generators.
Utah has also begun incorporating drone technology into its program, with a 2024-2025 UAV seeding operation running in Cache Valley. The shift toward automation and remote operation is making seeding cheaper and safer, since ground crews no longer need to access remote mountain generators during winter storms.
Environmental and Safety Concerns
Silver iodide is the most commonly used seeding agent, and questions about its environmental impact come up regularly. Silver is toxic to soil microorganisms and can inhibit bacterial enzymes, so the concern isn’t unfounded. Precipitation from seeded clouds contains measurably more silver than natural rainfall: concentrations of 10 to 4,500 nanograms per liter compared to 0 to 20 nanograms per liter in unseeded rain.
However, the quantities involved are small in absolute terms. The Agency for Toxic Substances and Disease Registry notes that silver released through cloud seeding has decreased over the years and is not expected to contribute significant amounts to water supplies. For context, the major sources of silver contamination in soil come from industrial activities like mining, sewage sludge disposal, and the former photographic industry, not cloud seeding. Background silver levels in fresh water average about 0.2 micrograms per liter, and seeding contributions remain well below thresholds of concern for drinking water.
The Dubai Flooding Question
When severe flooding hit Dubai in April 2024, cloud seeding quickly became a popular explanation on social media. The reality was more straightforward. Meteorological analysis of the event found that the cloud seeding hypothesis doesn’t hold up, primarily because Oman, Bahrain, Qatar, and Iran all experienced similar rainstorms and flash floods at the same time. Cloud seeding operations don’t produce widespread, large-scale extreme precipitation events. The Dubai flooding was driven by a powerful regional weather system, not artificial intervention.
Who Regulates It
In the United States, anyone conducting cloud seeding must report their activities to NOAA at least 10 days before starting, under the Weather Modification Reporting Act of 1972. A follow-up report is required after operations conclude. Failure to report can result in fines up to $10,000. The federal definition of weather modification is broad, covering anything from dispersing substances into clouds to using lasers or electromagnetic radiation on the atmosphere.
NOAA’s role is primarily record-keeping rather than approval. The actual permitting and oversight happens at the state level, where individual programs set their own rules about when, where, and how seeding can occur. States with long-running programs like Utah and Wyoming have decades of operational data and established regulatory frameworks governing their projects.