Skip to content

Monday, Jul. 21, 2025

Has cloud seeding triggered extreme flooding in Colorado?

Tyler Hickman, The Colorado Sun
no

Multiple studies show that cloud seeding does not increase rain or snowfall enough to trigger extreme flooding, and scientists say there is no evidence the practice contributes to weather disasters. 

Cloud seeding is a weather modification tactic where substances like silver iodide are released into clouds to encourage more rain or snowfall, often in drought-prone regions.

Data on the efficacy of cloud seeding varies. A 2018 report from the World Meteorological Organization, a United Nations agency that promotes international cooperation on atmospheric science and climatology, showed cloud seeding increases precipitation anywhere from 0% to 20% due to the weather’s natural unpredictability.

Researchers in Idaho found cloud seeding could add anywhere from .05 to .28 millimeters — roughly the thickness of fishing line — to snow accumulation.

Colorado, one of nine states actively cloud seeding, has had a weather modification permit program since 1972, with seven winter operations currently running throughout the state. 

This fact brief is responsive to conversations such as this one.

Sources

About fact briefs

Fact briefs are bite-sized, well-sourced explanations that offer clear "yes" or "no" answers to questions, confusions, and unsupported claims circulating online. They rely on publicly available data and documents, often from the original source. Fact briefs are written and published by Gigafact contributor publications.

See all fact briefs

The Colorado Sun is a journalist-founded, award-winning and nonprofit news outlet based in Denver that strives to cover all of Colorado so that our state — our community — can better understand itself. In this way, we believe we can contribute to a more vibrant, informed and whole Colorado. We are committed to fact-based, in-depth and nonpartisan journalism. We cover everything from politics and culture to the outdoor industry and education. Our goal is to produce the best possible journalism. We do that with the help of you, our readers, and community backers. We launched on Sept. 10, 2018.

Learn More

Latest Fact Briefs

Be a Friend of facts

Help us fund more great fact briefs like this one.