Major flood disasters in Asia and the United States of America have caused heavy casualties and economic losses in July, highlighting the dangers and the challenges in ensuring that early warnings reach those who need them.
India, Nepal, Pakistan, the Republic of Korea were among the countries affected in Asia, with hundreds of lives lost, whilst flash flooding in the US states of Texas and New Mexico also killed more than 100 people.
Storms drenched southern parts of the Chinese mainland on 21 July, triggering warnings of flash floods and landslides, a day after Typhoon Wipha pounded Hong Kong.
"Flash floods are not new, but their frequency and intensity are increasing in many regions due to rapid urbanization, land-use change, and a changing climate. Rising temperatures play a role because each additional degree Celsius of temperature increase allows the atmosphere to hold about 7% more water vapor, according to the law of thermodynamics. This is increasing the risk of more extreme rainfall events. At the same time, glacier-related flood hazards are increasing due to enhanced ice melting in a warmer climate," said Stefan Uhlenbrook, Director of Hydrology, Water and Cryosphere at WMO.
"Floods and flash floods pose major threats to lives and infrastructure, claiming thousands of lives each year. They are therefore one of the key priorities of the Early Warnings for All initiative," said Hwirin Kim Chief of Hydrological Water Resources Services Division at WMO.
Monsoon-related floods
India: Heavy monsoon rainfall severed transport links and destroyed infrastructure. The India Meteorological Department on 21 July warned that heavy to very heavy rainfall was likely to continue over many parts of the country, with a risk of landslides and flash flooding.
Pakistan declared a state of emergency in the worst affected areas and sent in army helicopters for the rescue and relief effort. The Pakistan Meteorological Department warned of an exceptional high flood threat in the upper catchments of the river Jhelum - one of the major rivers running through the country.
Republic of Korea: From 16-20 July, some areas in the southern part of the country received record rainfall of more than 115 mm per hour. The President declared a special disaster zones and activated national emergency management mechanisms.
There were at least 18 confirmed deaths, with dozens injured. More than 13,000 people were evacuated from their homes. There was widespread damage to property, roads and infrastructure and disruption to energy supplies and transport. The area around Sancheong was devastated by a landslide after more than 800 mm of rain fell within several days in a mountainous area which was previously hit by a wildfire which destroyed trees and roots capable of absorbing the water.
Glacier-related hazards
A devastating flood swept through Nepal's Rasuwa district on 7 July, not due to rain but apparently to a glacial lake outburst over the border in China's Tibet Autonomous Region. Initial reports said seven people died and 19 people were missing. It destroyed hydropower capacity, swept away an important bridge and disrupted cross-border trade.
The flood was caused by the sudden draining of a 'supraglacial' lake that started forming as a small pond in end of December 2024 and grew significantly in June 2025, according to the International Centre for Integrated Mountain Development (ICIMOD), which is based in the Nepalese capital Kathmandu and is supporting WMO and other partners during the ongoing International Year of Glaciers' Preservation .
In a press statement , ICIMOD scientists expressed shock at the increased frequency of glacial origin hazards .
- In the 2000s experts would anticipate a glacial origin flood to hit the Hindu Kush Himalaya region once every 5 to 10 years.
- In two months - May and June 2025 alone saw three glacial origin floods hit the region, in Nepal (Limi), in Afghanistan (Andorab valley) and Pakistan (Chitral, Hunza).
- On 7 July, there was not just one, but two glacial origin floods strike Nepal: in Rasuwa, and in Upper Mustang.
- A three-fold increase in Glacier Lake Outburst Floods (GLOF) risk across HKH is projected by the end of the 21st century.
Supraglacial lakes form on the surface of glaciers, particularly in debris-covered areas. They are highly dynamic, often beginning as small meltwater ponds that gradually expand and sometimes merge to form larger supraglacial lakes. The detection of these lakes largely depends on the spatial resolution of satellite imagery.
Temperature rise is known to play a key role in the increasing frequency of glacial origin floods.
WMO is working to increase global awareness of the short-term hazards of glacier melt this year during the International Year of the Glaciers' Preservation , as well as to strengthen observations and monitoring through its Global Cryosphere Watch Programme .
Texas Hill Country Floods
More than 100 people were confirmed dead and dozens more missing after months worth of rain fell in the space of a few hours in Texas Hill Country on 4 July. Many of the victims were young children at vacation camps swept up in the swollen river waters.
The US National Weather Service issued a flash flood watch for Kerr County more than 12 hours in advance. This was upgraded to a flash flood warning about three hours ahead of time, culminating in a flash flood emergency, which was disseminated by Weather Radio, emergency management systems, and TV/radio.
But one of the challenges was that the final warnings came as people were sleeping and there were no local sirens in the camps. Floodwaters surged dramatically at about 4 a.m., with the Guadalupe river jumping 26 feet (nearly 8 meters) in 45 minutes.
Tropical moisture from a tropical storm that struck Mexico south of Texas coupled with a storm system from Northwestern Mexico caused a mesoscale convective complex to develop over the central Texas Hill Country late on 3 to 4 July. This produced 10-18 inches (25-46 cm) with a maximum of 18 inches of rain in a few hours, rapidly overwhelming the Guadalupe River basin in Kerr County.
The steep, rocky terrain of the Hill Country caused minimal rainfall absorption, promoting rapid runoff.
Flash Floods
Accounting for approximately 85% of flooding cases, flash floods also have the highest mortality rate among different classes of flooding, including riverine and coastal.
A flash flood is defined as a sudden, high-intensity flood event where the time between the triggering event (typically intense rainfall) and the onset of flooding is within a few hours. These events are characterized by rapid water level rise, high peak river discharge, and often devastating impacts on infrastructure and communities, especially in urban and mountainous areas - as was the case with Texas.
Unlike slow-onset river floods, flash floods leave very limited time for reaction, making accurate short-term forecasting and community preparedness essential. That is why WMO emphasizes both technological innovation and training in hazard forecasting, early warning dissemination, and risk communication.
Flash floods alone account for nearly 85% of all flooding-related fatalities and result in economic losses exceeding $50 billion annually. A global study by the World Bank estimates that 1.81 billion people (23% of the world population) are directly exposed to 1-in-100-year floods, with 89% of them residing in low- and middle-income countries.
Recent catastrophic floods highlight the urgent necessity for improved forecasting and warning systems:
- 2020 South Asian Floods: Affected over six countries, causing 6,511 fatalities and US$ 105 billion in damages.
- 2022 Pakistan Floods: 1,700+ casualties, 33 million people affected, with estimated losses of US$ 40 billion.
- 2024 Europe, Middle East and Africa Floods: Resulted in US$ 36 billion in economic damages.
WMO Action
WMO supports countries in predicting flash floods through the Flash Flood Guidance System (FFGS) under Flood Forecasting Initiative (FFI), a real-time forecasting and early warning platform used in over 70 countries.
This system integrates satellite precipitation, radar, and high-resolution numerical weather models to support forecasters in identifying local flash flood threats. The operational backbone includes a network of regional centres and national services trained to interpret and act on the guidance, often hours before rainfall-triggered flooding begins.
WMO and partners of Flash Flood Guidance System with Global Coverage are transitioning FFGS into a globally governed, Member-led system, and working towards its sustainability and interoperability to ensure live saving flash flood warnings and products are integrated into the Multi-Hazard Early Warning System framework of WMO Members.
Beyond the tools themselves, WMO plays a convening role by building national capacity, certifying hundreds of experts under a Flash Flood Forecasting Competency Framework, and facilitating real-time coordination between forecasting agencies and disaster managers.
