Cloudburst: Causes and Impacts

According to the Indian Meteorological Department, a cloudburst refers to an extreme weather phenomenon that involves sudden, intense, and exceptionally heavy downpour of over 100 mm. This severe rainfall is restricted to a small area of 20 to 30 square km and lasts for a short span of time, i.e., from a few minutes to an hour. It is often accompanied by hailstorms, thunder, and lightning.

Unlike the monsoon rains that are consistent and fall on a large area of land, the cloudburst occurs in a small local place. As a result, this small local place gets soaked up completely with an enormous amount of water. Often such events overburden natural drainage systems, resulting in flash floods, dangerous mudflows, and massive landslides, particularly in hilly and high mountainous regions of South Asia. These may wipe out entire villages and districts, which may turn into piles of mud and rubble within minutes. Urban areas are also vulnerable, as heavy localised rainfall can flood streets, damage infrastructure, and disrupt normal life. Rapid urbanisation, encroachment on natural drainage channels, and deforestation further amplify the impact.

Why Cloudburst Occurs

Cloudbursts occur due to the sudden release of accumulated water in clouds. When the air gets hot due to the sun’s heat, it rises up in the sky towards the clouds. This rising hot air current prevents the dense clouds from releasing rain temporarily. So, the clouds become heavier due to excessive condensation along higher altitudes. These water droplets enlarge in size instead of falling down as rain because hot air blocks their fall. Eventually, the upward air current weakens; clouds become too heavy to hold more water; and rain falls down intensely and rapidly on a small patch of land. This usually happens at an altitude of 1,000 to 2,500 metres above sea level.

Reasons for Common Occurrence of Cloudbursts in Mountainous Regions

Mountainous regions are more prone to cloudbursts due to a combination of topography, wind patterns, and local meteorology.

Some of the key reasons are as follows:

• Mountainous regions have steep slopes, which facilitate the swift upward movement of air over slopes. This, in turn, promotes the formation of clouds.
• These regions are often characterised by narrow valleys, that trap the clouds, concentrating rainfall over small areas. As a result, these clouds produce heavy localised downpours in these areas.
• In mountainous regions, storm systems are often small and isolated. Due to these systems, heavy downpour may occur at one place instead of spreading over a larger area.
• In India, the interaction of monsoon winds with mountainous terrain is a major factor. Moisture-laden winds from the Arabian Sea and Bay of Bengal move towards the Himalayas and Western Ghats. When these winds encounter steep slopes, the air is forced to rise rapidly, cool, and condense into dense clouds, a process known as Orographic lift.

Can Cloudbursts be Forecast?

Accurate forecasting of cloudbursts is extremely challenging because of the following reasons:

• They have a minuscule scale in area (20–30 km²) and time (few minutes to an hour).
• Such events cannot be predicted easily, as their rapid formation and small scale prevent them to be recorded in numerical models.
• There is frequent development of small and swift thunderstorms in India’s mountainous and tropical regions. So, they cannot be predicted exactly.
• Besides, there are complications in the related atmospheric processes between topography, convection, moisture, and wind patterns in our country and other such tropical regions.
• Further, cloudbursts often occur over distant high hills that are beyond the reach of observatories. Thus, they remain unnoticed and unrecorded.
• Not much is known about cloudburst. During such events, scientists become sceptical if they are cloudbursts or any other event like glacial outburst floods. So, forecasting, understanding, and monitoring of these events become difficult.
• Climate change has made cloudbursts more intense and frequent, increasing their unpredictability.
• The lack of high-resolution, real-time meteorological data in these regions limits the issuance of timely warnings.

Current Cloudbursts Monitoring Systems To address these challenges Indian Meteorological Department (IMD) uses a combination of technologies:

• Doppler weather radar (DWR) network and its surface observation network examine thunderstorms, i.e., rain clouds with lightning, responsible for cloudbursts.
• Radar network systems provide information on wind speed, cloud images, and storm velocity every ten minutes, allowing short-term ‘nowcasts’ with a few hours lead time.
• Numerical weather prediction (NWP) models, high-resolution models that simulate local weather patterns and help predict potential thunderstorms.
• Remote sensing satellites, including the NASA-ISRO NISAR, assist in multi-hazard assessment, risk mapping, and early warning.

Some Major Incidents of Cloudburst in India

India has witnessed several devastating cloudburst events in recent decades, particularly in Uttarakhand, Himachal Pradesh, and southern states. Some major incidents are mentioned below:

• August 17, 1998, Malpa (Uttarakhand): Heavy rain and cloudburst led to a massive landslide in Malpa village. Consequently, there were 250 casualties including 60 pilgrims of Kailash Manasarovar in Kali valley of Pithoragarh.
• July 6, 2004, Alakananda river (Chamoli, Uttarakhand): Severe landslides washed away three vehicles killing 17 people and injuring 28 people. Besides, almost 5,000 pilgrims were stranded near the Badrinath Shrine.
• August 7, 2009, Nachni (Munsyari, Pithoragarh): A cloudburst occurred in Nachni region close to Munsyari, led to a severe landslide, killing 38 people in the region.
• September 15, 2010, Almora (Uttarakhand): Two villages got completely submerged due to a cloudburst.
• June 15, 2013, Kedarnath and Rambara region (Rudraprayag district, Uttarakhand): A severe cloudburst occurred that led to more than 1,000 casualties in this district. Even after a fortnight of the incident, thousands were still missing in the region. Neighbouring districts of Uttarkashi, Tehri, Chamoli, and Pithoragarh were also affected which led to over 6,000 casualties.
• September 14, 2013, Rudraprayag (Uttarakhand): A cloudburst occurred at Ukhimath, which led to 39 casualties.
• September 29, 2010, NDA Khadakwasla, (Pune, Maharashtra): A cloudburst occurred that gave way to flash floods. As a result, many people were wounded along with damaging several vehicles and buildings. After a fortnight or so, a cloudburst at Pashan, Pune, led to 4 casualties and many injured along with severe damage.
• 2015, 2018 and 2021 (southern states): Cloudbursts recorded maximum rainfall of 494 mm in one day.
• 2022, Pahalgam (Jammu and Kashmir): Cloudburst affected pilgrims visiting Amarnath Cave.
• 2023 (Himachal Pradesh): During the monsoon season, the number of cloudbursts increased at several places in Himachal Pradesh such as; Shimla, Solan, and Mandi causing considerable loss of life and property.
• 2024, Uttarakhand and Himachal Pradesh: More than 50 cloudburst disasters occurred, led to 400 casualties and affecting more than 200 villages.

Dharali Disaster On August 5, 2025, flash floods in Dharali and Harsil villages (Uttarakhand) caused massive destruction due to heavy downpour. Owing to these floods, water filled with debris flowed over villages in the state. The sudden flood took a toll on life and property, washing away houses, buildings, bridges, and roads. A number of buildings even got submerged under the strong flow of water filled with mud and debris. A large number of people got trapped under the landslide. This disaster is a reflection of both natural triggers and human-induced vulnerabilities. It is believed that the reason for such destruction could be inappropriate and reckless development on hill slopes, blasting process to built tunnels, quarries, roads and dams as these have destabilised slopes.

The Indian Space Research Organisation (ISRO) received satellite data regarding the Dharali Flood. According to this data, a flash flood occurred in the region of Dharali (Uttarakhand). It was characterised by the following:

• Stream channels had been broadened.
• The shape and structure of a river course was altered.
• Its floodplains were changed drastically.
• Drastic impact was there on human lives and infrastructure.
• A large amount of sediment and debris were deposited over an area of 20 hectares, where Kheer Gad and Bhagirathi rivers meet.

Why Cloudbursts are so Destructive

• The people living in remote regions, where the cloudbursts often occur, lack literacy, speak different languages, do not have basic facilities, and effective communication channels, which reduces awareness and reporting of cloudburst threats.
• The infrastructure is not adequate in these regions. So, people have to bear more loss due to cloudburst.
• The local authorities in these remote regions may lack resources or proper functioning, delaying response.
• Early warning systems are often absent or ineffective in these regions.
• Unchecked construction activities and reckless cutting down of trees aggravate the impact of cloudbursts. These result in devastating landslides and mudslides, carrying timber and boulders with them, which is highly dangerous.
• There is less time for preparedness, so people cannot evacuate the place before the cloudburst disaster.

Unchecked Development Activities and Impact of Cloudburst

The Dharali flash flood (2025) highlights the importance of early warning systems and the need for prompt action in the regions facing cloudburst. This disaster threw light on the vulnerable hilly terrain of the Himalayan region and the risks of unsustainable hill development. Contractors often initiate the blasting of rocks by using explosives, regardless of the multiple risks posed by this action and the vulnerability it creates. Then, they construct tunnels, roads, highways and dams, which make the hilly slopes unstable. This is more so often in the regions where environmental impact of such construction is not assessed before construction works starts.

How to Mitigate the Impact of Cloudburst

In disaster-prone regions, multi-hazard risk assessment must be carried out regularly with the help of advanced technologies like AI, machine learning tools, geo-informatics, drones, and big data analytics. Besides, water levels in dams, canals, rivers, etc. must be assessed by Internet of Things (IoT) sensors. Flash flood damage can be mitigated by strengthening bridges, dams and streams flowing through tunnels. 

India must tap into the skills and talents of disaster management practitioners who have substantial experience in disaster risk reduction. They work at several renowned scientific and technical institutions, research institutions, academic institutions and other such organisations.

In July 2025, NASA-ISRO Synthetic Aperture Radar (NISAR) satellite was launched. This satellite can assist in remote sensing while carrying out multi-hazard risk assessment in disaster-prone regions. This may also contribute to early warning messages and risk-informed alert.

Thus, early warning systems must be strengthened. Construction of settlements, roads, and tunnels along with mining must be prohibited in hazardous zones. Also, climate-resilient infrastructure must be built.

Conclusion

Cloudbursts are among the most devastating natural phenomena that can submerge large areas of land and can lead to loss of life and property. The conditions for cloudbursts emerge naturally in hilly and mountainous regions. However, climate change has made them more frequent and intense. India needs to improve on forecasting techniques and reinforce resilience of the communities living in cloudburst-prone mountainous regions by strengthened preparedness, technological monitoring, and sustainable development practices, to mitigate the devastating effects of future cloudbursts.

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