The UN World Meteorological Organization (WMO) said that the tragedy highlights growing global challenges around extreme rainfall, warning dissemination and community preparedness.

Flash floods are the most lethal form of flooding, responsible for over 5,000 deaths annually and 85 per cent of all flood-related fatalities worldwide, according to WMO data, and result in economic losses of more than $50 billion annually.

“Unlike slow-onset river floods, flash floods leave very limited time for reaction,” the agency said in a news release on Wednesday.

“That makes accurate short-term forecasting and community preparedness essential.”

Months of rains in hours

Overnight 3 into 4 July, torrential rains – up to 46 centimetres (about 18 inches) in a matter of hours – sent a wall of water surging through Kerr County’s Guadalupe River basin at around 4 AM, catching many residents and vacationers off guard.

The US National Weather Service issued timely alerts – including a flash flood watch more than 12 hours in advance, upgraded to a flash flood emergency about three hours before impact.

The warnings were disseminated by Weather Radio, emergency management systems and television and radio stations, but many people, including hundreds of children at summer camps, were not reached in time.

Floodwaters surged dramatically as the Guadalupe River rose nearly 8 metres (about 26 feet) in about 45 minutes.

Among the hardest hit was the all-girls summer camp, Camp Mystic, along the river, where at least 27 campers and counsellors died, according to media reports. Texas state authorities report that more than 160 people remain missing.

The disaster has triggered one of the largest search-and-rescue efforts in state history.

More frequent and severe floods

Flash floods are not new, but their frequency and intensity are increasing in many regions due to rapid urbanization, land-use change and a warming climate.

“A warmer atmosphere holds more moisture and so this means that extreme rainfall events are becoming more frequent,” WMO said.

The Texas disaster joins a string of recent catastrophic floods. In 2022, flash floods in Pakistan killed over 1,700 people and displaced millions. In 2024, floods in Europe, the Middle East and Africa saw $36 billion in economic damages.

And just this week, a flash flood along the Nepalese-Chinese border swept away the main bridge linking the two countries.

Supporting countries

To help countries predict such hazards, WMO operates the Flash Flood Guidance System, a real-time forecasting platform used in over 70 countries. It integrates satellite data, radar, and weather models to detect local flash flood threats and supports training programs to build national capacity.

Beyond technology, the agency plays a convening role by building national capacity, certifying experts, and facilitating real-time coordination between forecasting agencies and disaster managers.