In the aftermath of devastating floods in Texas, social media users have spread misinformation that cloud seeding is to blame. Meteorologists have been quick to debunk the claim, but the rumours underline how weather can be a magnet for conspiracy theories.

There is no evidence that weather modification activities caused the extreme rainfall in Texas, which triggered flash flooding on July 4 and claimed at least 89 lives. Days before the deluge that brought over a foot of rain, the US National Weather Service warned of locally heavy precipitation in parts of Texas and the Southwest brought by monsoonal moisture, as well as remnants of a tropical storm that made landfall in Mexico the week prior.

But on social media, prominent accounts with large followings amplified claims suggesting that the Texas floods may have been caused by cloud seeding, a form of weather modification.

By now, it’s a familiar pattern: An extreme weather event occurs, and unfounded theories about its cause quickly emerge and spread online. Often, those claims crumble on closer scrutiny of the facts. Similar conspiracies that cloud seeding caused damaging floods across the United Arab Emirates popped up last year – assertions that meteorologists quickly debunked.

"I understand why emotions are running high and people are scrutinizing cloud seeding to see if it’s to blame,” said Augustus Doricko, Rainmaker Technology Corp. chief executive officer. "Categorically, it’s not.”

According to Doricko, Rainmaker flew a brief 20-minute cloud seeding mission in south-central Texas last Tuesday, but suspended all operations that same day due to abnormally high moisture content in the air. The two clouds seeded during the Tuesday flight would have dissipated after a few hours and would have had no effect on the floods several days later, he added. 

Cloud seeding involves using chemicals, often particles of silver iodide, to trigger the formation of ice crystals or droplets from water that’s already present in a cloud but not being efficiently turned into rain. Though the technique has been studied for decades, it remains difficult to predict the additional rainfall that cloud seeding operations can generate, with estimates ranging widely from 0% to 20%.

What’s clear is that the technique would not have been able to generate the record-breaking rainfall seen in Texas. So much rain fell that the Guadalupe River at Kerrville, one of the epicenters of the floods, rose some 26 feet (8 meters) in less than an hour overnight on Friday.

"Based on the meteorological evidence, the Texas floods were caused by a powerful natural weather system, with thunderstorms fed by very moist air from the warm Gulf of Mexico,” said Andrew Charlton-Perez, professor of meteorology at the University of Reading in the UK.

He added that weather balloon data collected the day prior to the floods yielded very high atmospheric moisture readings, and that the National Weather Service had predicted very high rainfall totals in advance. 

"Cloud seeding played ZERO role in deadly Texas floods,” Matthew Cappucci, a meteorologist, wrote on X. "Rudimentary, basic physics explains that.”

Emergency managers and families are also dealing with other sources of misinformation, Kerrville City Manager Dalton Rice said at a Monday press conference. They include fake calls and scammers claiming they have missing children and will return them for money.

Doricko said he hopes to see a clearer regulatory framework around cloud seeding and greater public awareness of the effects and limits of weather modification technologies. 

"That would mitigate people’s unfounded concerns around weather modification when severe weather events like this happen,” he said. – Bloomberg