Cloud seeding is carried out by governments, water utilities, ski resorts, and agricultural groups across more than 50 countries. The largest programs are run by national governments in China, the United Arab Emirates, and the United States, but much of the day-to-day work is funded by smaller players like municipal water districts, farming cooperatives, and even individual ski areas looking for a few extra inches of snow.
Countries With Active Programs
China operates the world’s largest cloud seeding program by a wide margin. The Chinese government has set targets for artificial rainfall and snowfall operations covering more than 5.5 million square kilometers, roughly 57% of the country’s total land area. A separate hail suppression effort covers another 580,000 square kilometers. These operations support agriculture, wildfire response, and ecological restoration across dozens of provinces.
The United Arab Emirates has invested heavily in rain enhancement research through its National Center of Meteorology, building dedicated infrastructure including a high-performance computing system, a Weather Enhancement Technology factory, cloud seeding aircraft, and ground-based generators. For a desert nation that averages just a few inches of rain per year, even modest gains in precipitation carry outsized value.
The World Meteorological Organization maintains a register of countries reporting weather modification projects. As of its most recent published data, reporting nations included Russia, Japan, South Korea, Mongolia, Morocco, South Africa, Jordan, Malaysia, Canada, Germany, and several others across Europe, Central Asia, and the Caribbean. The true global count is likely higher, since reporting to the WMO is voluntary and many programs go unregistered.
US States Running Cloud Seeding Programs
As of July 2024, at least nine US states had active cloud seeding programs: California, Colorado, Idaho, Nevada, New Mexico, North Dakota, Texas, Utah, and Wyoming. Ten other states have banned or considered banning cloud seeding or weather modification entirely. The split reflects a genuine tension in the American West, where water is scarce and downstream neighbors worry about one state pulling rain out of clouds before they drift across the border.
The goals vary by state and season. In winter, programs in mountain states like Colorado, Utah, and Wyoming seed clouds passing over mountain ranges to boost snowpack. That snowpack melts in spring and feeds the reservoirs that supply cities, farms, and hydroelectric plants for the rest of the year. In summer, states like Texas and North Dakota focus on seeding thunderstorms to reduce the severity of hail, which can devastate crops in minutes.
Water Utilities and Ski Resorts
Some of the most consistent cloud seeding funding in the US comes not from state legislatures but from water utilities and ski resorts with a direct financial stake in snowfall. Denver Water, one of Colorado’s largest water providers, partners with the Colorado Water Conservation Board, the Colorado River Water Conservation District, and water utilities in Arizona, southern California, and Nevada to fund cloud seeding operations during winter months.
Ski areas are part of that same coalition. Breckenridge, Keystone, and Winter Park all help fund Colorado’s cloud seeding program. As Winter Park’s planning director has put it, the resort has been cloud seeding on and off for 30 years: a few extra inches of snow benefits skiers in the short term, and when it melts, it benefits water supply downstream. It’s a rare case where recreation and resource management align perfectly.
Agricultural Hail Suppression
Farmers and agricultural groups have used cloud seeding for hail suppression in more than 50 countries since the 1970s. The logic is straightforward: seeding a developing thunderstorm introduces extra particles for ice to form around, producing many smaller hailstones instead of fewer large, destructive ones. A county-level study in Kansas examined data from 2002 to 2020 and looked at hail size, hail frequency, crop damage, crop yields, and potential effects downwind to assess whether the programs actually worked. In states like North Dakota and Texas, farming cooperatives and county governments fund these programs directly, pooling resources to hire operators who monitor radar and dispatch seeding aircraft when threatening storms develop.
How Cloud Seeding Works in Practice
The materials used depend on the type of cloud. For cold clouds, where temperatures are below freezing, operators release silver iodide from flares mounted on aircraft or from ground-based generators positioned upwind of a target area. Silver iodide has a crystal structure similar to natural ice, so it gives supercooled water droplets something to freeze onto, forming ice crystals that grow heavy enough to fall as snow or rain. For warm clouds, operators use salts like calcium chloride or sodium chloride, which attract moisture and encourage tiny cloud droplets to collide and merge into raindrops large enough to reach the ground.
The quantities involved are surprisingly small. In one set of aviation experiments, a cold-cloud seeding run used just 23 flares containing about 16 grams of silver iodide each, while a warm-cloud operation dispersed 1,500 kilograms of salt powder along with calcium chloride flares. Most studies suggest cloud seeding increases precipitation by only 5 to 15 percent compared to what would have fallen naturally. That may sound modest, but over an entire winter season across a mountain range, even a 10 percent boost in snowpack can translate into billions of gallons of additional water supply.
Environmental and Regulatory Concerns
Silver iodide is nearly insoluble, meaning it doesn’t dissolve easily in water. A 2024 review by the U.S. Government Accountability Office found that existing research, while limited, suggests silver iodide does not pose an environmental or health concern at current levels. The caveat is that no one has studied what happens if cloud seeding scales up dramatically. When silver iodide does dissolve, it releases small amounts of silver ions, which at high enough concentrations could harm beneficial bacteria in soil and water. The EPA has noted that any new seeding agents may require its approval, but no comprehensive federal regulation currently governs cloud seeding operations in the United States.
States fill some of that gap. The ten states that have banned or considered banning weather modification reflect concerns about environmental effects, property rights over rainfall, and the difficulty of proving whether seeding actually caused a particular storm to produce more rain or less hail. For the nine states with active programs, oversight typically falls to state water boards or departments of natural resources, which issue permits and require operators to report what materials they use and where.