Laws passed

Prohibits the intentional release or dispersion, by burning of fuel, of chemicals into the environment of this state with the express purpose of affecting temperature. (8/1/26)

Senator Fesi returns to amend the atmospheric modification ban he authored just last year, adding seven words – “including by the burning of fuel in an aircraft engine” – to a prohibition that already covers dispersal “by any means,” making this less a legal expansion than a pointed declaration about what his law was always meant to cover.

Became Act No. 601 without the Governor's signature.

Amends and adds to existing law to revise provisions regarding cloud seeding programs.

Idaho S1269 adds transparency guardrails to the state's established cloud seeding program, requiring public meetings, annual environmental impact reports, and monthly operator reporting — while notably narrowing the program's existing absolute liability shield by allowing claims based on gross negligence or willful misconduct.

Geoengineering and Weather Modification Activities

Florida becomes the second state, after Tennessee, to ban weather modification, but goes substantially further by creating a mandatory airport surveillance network, establishing felony-level penalties with fines up to $100,000, and completely dismantling its 68-year-old weather modification licensing program rather than simply prohibiting new activities under it.

Now codified as Chapter 2025-157, Laws of Florida

Makes an appropriation to the Desert Research Institute of the Nevada System of Higher Education to support the Nevada State Cloud Seeding Program. (BDR S-389)

Nevada's 2025 cloud seeding appropriation demonstrates the stark policy divide among western states—while neighbouring states debate geoengineering bans, Nevada continues funding weather modification as routine water infrastructure, unanimously passing its third consecutive biennial appropriation for the program.

To prohibit the intentional release, or dispersion of chemicals into the environment of this state with the express purpose of affecting temperature. (8/1/25)

Louisiana becomes the latest state to enact a geoengineering prohibition, but uniquely accomplishes this by simultaneously repealing its existing weather modification licensing framework, effectively transitioning from regulated permission to outright ban.

Enacted as Act No. 95 of the 2025 Regular Session.

To memorialize Congress to investigate geoengineering in Louisiana.

Louisiana's legislature unanimously memorialises Congress to investigate geoengineering activities over the state, with the resolution's preamble explicitly referencing atmospheric trails "distinct from ordinary contrails" as a matter of public concern.

Adopted by both chambers; transmitted to Congress.

Repeals existing law to remove provisions regarding weather modification.

Idaho is cleaning house by repealing a dormant 1970s-era weather modification district law that was used by only one district and has sat unused for roughly 50 years. Unlike other states that have passed new geoengineering prohibitions, this is legislative housekeeping rather than a policy statement against weather modification.

As of 1 July 2025, Idaho will scrap the old rule that allowed counties to set up special “weather-modification districts.” Those districts—small local bodies that could tax residents to fund cloud-seeding or other weather-control projects—will be dissolved.

AN ACT to amend Tennessee Code Annotated, Title 4; Title 5; Title 6; Title 7; Title 8; Title 39; Title 42; Title 43; Title 44; Title 55; Title 58; Title 59; Title 60; Title 65; Title 68 and Title 69, relative to environmental protection.

Tennessee transformed a technical caption bill about permit timelines into a comprehensive atmospheric intervention ban through floor amendment, with enforcement tied to existing air quality violations rather than creating new criminal statutes.

Substituted by SB2691.

AN ACT to amend Tennessee Code Annotated, Title 4; Title 5; Title 6; Title 7; Title 8; Title 39; Title 42; Title 43; Title 44; Title 55; Title 58; Title 59; Title 60; Title 65; Title 68 and Title 69, relative to environmental protection.

Tennessee's geoengineering ban includes legislative findings asserting that federal atmospheric experiments may occur in the state, while its own fiscal analysis assumes no such activities are happening or will occur, creating an unusual disconnect between the stated justification and the projected impact.

Tennessee SB2691 passed both chambers and became Public Chapter 709 effective July 1, 2024.

Makes an appropriation to the Desert Research Institute of the Nevada System of Higher Education to support the Nevada State Cloud Seeding Program. (BDR S-592)

Nevada continued its legislative support for weather modification with this $1.2 million appropriation to fund the state's official cloud seeding program—demonstrating that while some states move to ban atmospheric intervention, others actively fund it as water supply infrastructure.

Adding notification requirements to the weather modification statute.

This bipartisan transparency bill sailed through the legislature with near-unanimous support (18-0 in the House committee, 5-0 in the Senate committee). It was signed into law by Governor Sununu, establishing public notification requirements for state weather modification programs. Notably, the statute this bill amended (RSA 12-F) is the same statute that HB 764 (2025) proposes to repeal entirely and replace with a prohibition on geoengineering.

Bill passed, became Chapter 34, effective July 16, 2021.

Adds to existing law to provide for cloud seeding in Idaho.

Idaho formalises its cloud seeding program with a sweeping liability shield and permit exemption—the state declares cloud seeding works and is in the public interest, then removes legal barriers that might otherwise allow affected parties to challenge operations in court.

Became Law April 16, 2021; Session Law Chapter 256

Study of weather modification

Montana House Joint Resolution 40 passed in 2019 directing a legislative study of weather modification laws to propose changes that would encourage increased use of cloud seeding technology for enhancing precipitation and water supplies.

Resolution filed with Secretary of State May 1 2019

Sunset Process Weather Modification

Colorado extended its cloud seeding permit program for 15 years while quietly eliminating a Cold War-era provision that had restricted weather operations affecting neighbouring states.

Enacted; Session Laws of Colorado 2018

House Resolution Amending The Membership And Extending The Reporting And Expiration Dates Of The Special Legislative Commission To Study The Establishment Of Procedures To Regulate And License The Intentional Manipulation Of The Global Environment Through Geoengineering (amends The Membership Of The Commission To Study The Regulation And Licensure Of Geoengineering From 5 To 7 Members And Extends The Reporting And Expiration Dates From April 2, 2018, To February 7, 2019, And Expires On May 7, 2019.)

Rhode Island House Resolution 7408, passed by the House in April 2018, extended the geoengineering study commission's deadline to February 2019 and expanded its membership from five to seven members, adding the Energy Resources Commissioner, an ecological scientist, a defence contractor representative, and a public member.

Waters and water rights; repealing the Oklahoma Weather Modification Act; effective date.

Oklahoma completely repealed its Weather Modification Act in 2015, eliminating state oversight of cloud seeding operations rather than adding restrictions. This represents the opposite trajectory of current 2025 legislative trends, where states are rushing to ban or regulate geoengineering activities.

HB 1420 became Chapter 102, effective November 1

Amends existing law to provide that under specified conditions a watermaster may acquire, hold and dispose of real and personal property, equipment and facilities for the proper administration of the water district and enhancement of water supplies, to provide that under specified conditions a watermaster may develop, coordinate or provide for certain weather modification projects; and to provide that if specified funds are not sufficient to cover expenses in implementing certain resolutions, such expenses shall come from assessments.

Idaho's first legislative step toward cloud seeding: rather than creating a statewide program, this 2015 law empowers individual water districts to authorise their watermasters to participate in weather modification projects.

Conclusion: Reported Signed by Governor on March 23, 2015; Session Law Chapter 82; Effective July 1, 2015.

Repeal certain obsolete provisions and references concerning weather modification programs.

A decade before South Dakota considered banning weather modification entirely, the legislature quietly removed the authority for counties to levy dedicated taxes for cloud seeding programs—not prohibiting the activity, but eliminating one funding pathway as obsolete.