Extreme Rainfall Events Pummel the Himalayas to California
- Khursheed Ahmad Shah and Rhysea Agrawal
- 6 hours ago
- 9 min read
Cloudbursts in India and atmospheric rivers in California are distinct weather phenomena, yet both unleash intense rainfall over a relatively short period. As climate change aggravates these events, there is an urgent need for governments to up their game in weather prediction.
When rains arrive in the Indian state of Jammu and Kashmir, they usually nourish crops, increase greenery, and create moderate weather conditions for tourists. But in August 2025, torrential rains ripped through the state’s Chositi village, killing 60 people and injuring over 100.
Scientists say this extreme rain event was a result of a cloudburst, a phenomenon where dense, moisture-laden clouds deliver an enormous amount of rain in a short period within a localized region, triggering flash floods and landslides.
Once rare, cloudbursts and their meteorological cousins, atmospheric rivers, are now increasing in frequency and intensity due to climate change: because a warmer atmosphere holds more moisture, when it rains, it pours. When this increased rainfall deposits more moisture than regional drainage systems, such as rivers and aquifers, can handle, it leads to floods that few countries and regions are immune to.
Kainat Aziz, postdoctoral fellow at the Centre for Sustainable Water Research at the Indian Institute of Technology Guwahati, says that in 2025, researchers observed considerable anomalies in the Arabian Sea surface temperatures.
“These strange events are connected to larger patterns of warming in the ocean, which speeds up evaporation and raises the amount of moisture in the air. Then, this extra moisture is moved across the Indian subcontinent, which makes rain episodes more intense,” she says.
Jammu and Kashmir experienced an exceptionally high frequency of cloudbursts in 2025. “This region experienced heavier and more frequent rainfall as a result of increased cyclonic activity caused by intensified western disturbances that originated in the Mediterranean,” Aziz says.
Even regions like Jammu and Kashmir that receive a lot of annual rainfall can be damaged by sudden cloudbursts. Intense rainfall often triggers flash floods and landslides, causing widespread destruction. It can also accelerate deforestation, trigger soil erosion, and sweep debris across landscapes, disrupting ecosystems.
Cloudbursts aren’t new meteorological phenomena, however. Recorded instances of these events date back at least 150 years, with one of the earliest documented events occurring in Porto Bello, Panama, in 1911. 63 mm (2.5 inches) of rain — nearly 40% of what that part of the country receives every year — fell in just three minutes.
According to Jayanarayanan Kuttippurath, an associate professor at the Centre for Oceans, Rivers, Atmosphere and Land Sciences at the Indian Institute of Technology Kharagpur, a cloudburst is typically defined as a rainfall event where 100 mm (4 inches) of rain or more falls within an hour over a small geographical area less than half the size of Manhattan.
In recent years, cloudbursts have drawn greater attention as research shows their increasing frequency under a warming climate. Scientists warn that higher ocean temperatures, particularly in the Indian Ocean, are fuelling heavier rains by loading the atmosphere with moisture.
A 2022 study that Kuttippurath coauthored shows that water vapor over India and the northern Indian Ocean has increased significantly: because water vapor traps heat, the region gets warmer, which allows the air to carry more moisture, creating a self-reinforcing loop. The paper suggests that this surge in moisture makes the atmosphere more prone to extreme rainfall, closely tying this to the intensification of cloudburst events in the Himalayas.
Global warming is also shifting the pattern of atmospheric jet streams — strong and narrow wind bands on the upper levels of the atmosphere — which in turn increases disturbances in India’s monsoon patterns. This is crucial for cloudburst events, Kuttippurath says, as most take place during the monsoons, when there is abundant moisture for cloud formation. The situation gets especially severe in the Himalayan slopes, where the phenomenon of orographic lifting — when rapid updrafts of air are forced upwards a mountain slope — leads to the creation of particularly dense clouds.
“As the air rises, it cools and condenses, resulting in intense, localised rainfall, which is an ideal condition for a cloudburst. In mountainous regions, such downpours lead to rapid runoff, often triggering flash floods and landslides,” Kuttippurath says.
Human activities such as deforestation and rapid construction have also played a role in increasing the risks from cloudbursts, as stripping the land of vegetation reduces its ability to soak up rainwater. This increases surface runoff and the risk of flooding.
Although it seems counterintuitive, these localized flooding events may also contribute to droughts in the affected regions. Because cloudbursts bring excessive rainfall in short periods of time, they do not sufficiently recharge water sources, including groundwater and aquifers. When these floods are followed by elongated dry periods, a phenomenon known as precipitation whiplash which is becoming increasingly common due to climate change, they can leave communities and wildlife unprepared to meet their water needs.
In July 2025, in the neighbouring state of Uttarakhand, a midnight cloudburst struck Mukh village, forcing terrified families to flee in darkness as the state’s disaster response teams rushed in. For residents of the fragile Himalayan belt, such disasters have now become almost a seasonal terror.
“The Himalaya is warming faster than the global average, leading to accelerated snow and glacier melt,” Kuttippurath says. “This adds additional moisture to the atmosphere, enhancing the conditions for heavy rainfall. Moreover, the unpredictable nature of these extreme weather events makes timely forecasting and preparedness particularly challenging.”
Tragic events like the Kedarnath disaster in 2013, along with recent cloudbursts in Darjeeling, Kishtwar, and Chamoli, have led to significant losses of life and missing people. Those who survive often face long-term psychological trauma, and many are left unhoused and unprepared, forced to move in search of safety and stability.
Since cloudbursts are local events and depend on small-scale atmospheric processes, it is difficult to predict them with any degree of accuracy. This is because most weather-forecasting algorithms are trained to model larger areas.
The High-Resolution Weather Research and Forecasting model and the Global Forecast System are among the many operational weather models that work with smaller spatial resolutions of 3 km to 12 km (1.9-7.5 miles). But they do not take into account the dynamics of steep topography, valley winds, or confined convection, which require even smaller spatial resolutions, of 1 km or less. “Models have greater difficulty getting correct temperature, humidity, and wind profiles in remote mountainous areas like Kishtwar or Gurez because there aren’t many ground-based measurements there,” Aziz says. The sampling frequency may also not be rapid enough to catch the precursors of a cloudburst, she added.
“To overcome these hurdles, we need targeted investments in ultra-high-resolution models, stronger observational networks, improved assimilation algorithms, and interdisciplinary approaches that bring together meteorology, hydrology, and remote sensing,” Aziz says. “Until such advances are put into practice, forecasting cloudbursts with precision will remain one of the toughest scientific challenges in mountainous regions like Jammu and Kashmir.”
As global warming makes the world warmer, several urban regions are now having to prepare for increased rainfall. One of these regions is the state of California, known for its arid and semi-arid landscapes, which has experienced six flooding events since 1980 that have cost the state over $1 billion in losses.
Climate change is bringing record-breaking floods to a state that is known as one of the drier parts of the contiguous United States: California.
The six large flooding events that California has experienced in the last 35 years have been a direct result of increased moisture from atmospheric rivers, a meteorological phenomenon where narrow and fast-moving bands of air currents transport significant amounts of water vapor, enough to form a “river.”
According to Rosa Luna-Niño, a postdoctoral scholar at the University of California, San Diego’s Scripps Institution of Oceanography, atmospheric rivers are typically long, on the order of thousands of kilometres, and relatively narrow, on the order of hundreds of kilometres. “These corridors of water vapor transport moisture from the tropics to higher latitudes over the ocean,” she says.
Although Californians have been hearing the term “atmospheric rivers” more frequently in recent years, this phenomenon is not new to the Golden State. Before this term gained popularity, these bands of moisture have been known by terms such as “plumes of humidity” and “Pineapple Express,” a term used for the atmospheric rivers that affect California due to their origin near the Hawaiian islands in the Pacific Ocean — and their significant contribution to Hawaii’s pineapple harvests.
In fact, atmospheric rivers are responsible for supplying about half of California’s freshwater in a given year, according to meteorologists at the California Department of Water Resources. In that sense, Luna-Niño says, “atmospheric rivers are both beneficial and hazardous.”
Although both cloudbursts and atmospheric rivers have recently caused major flooding events that have led to the destruction of human settlements, these events are meteorologically quite different, says Jesse Norris, a climate scientist at the University of California, Los Angeles.
“Atmospheric rivers are typically generated by a mid-latitude low-pressure system, known as an extratropical cyclone, and occur predominantly in winter,” he says. “Meanwhile, cloudbursts last for a much shorter time than atmospheric rivers, but potentially deposit just as much or more precipitation in total, and are more likely to occur in summertime.”
One common aspect between the two meteorological phenomena, Luna-Niño says, is topography. “Topography is relevant to atmospheric rivers in transforming water vapor into rainfall and snow, and it plays a crucial role in the development of convective deep clouds, particularly in the formation of cloudbursts.”
It is also possible for localized storms like cloudbursts to occur within atmospheric river events. San Diego County experienced a short-lived local storm on Jan. 22, 2024, that delivered about 3 inches (76 mm) of rainfall in less than an hour. This storm, brought on by an atmospheric river event, was classified as a “convective local storm,” belonging to the same category of storms as cloudbursts.
Norris says that the popularity of the term “atmospheric rivers” may also be a result of more intense rainfall events in California in the past few decades, attributed by climate scientists to global warming. “People should be aware that atmospheric rivers are holding more moisture as the climate warms. This means that they can cause heavier rain than in the past and are more likely to cause flooding,” Norris says.
This can especially be of concern if multiple atmospheric rivers occur in the same location at the same time in California, Norris says. “If one atmospheric river dumps substantial rain when the ground is already saturated from the previous atmospheric river, the risk of flooding and mudslides is far greater,” he says.
In early 2023, California experienced a cluster of nine atmospheric rivers at the same time, resulting in a series of record-breaking storms that dumped snow and rain across the state. The resultant floods and mudslides caused 21 deaths, several injuries, and over $3 billion in economic losses.
Research from Stanford University shows that atmospheric river clusters such as these increase the overall economic damage compared to single atmospheric river events, as the strongest atmospheric rivers are likely to be one in a sequence of many. The study also stated that climate change will likely increase the frequency of extreme atmospheric rivers and make losses like these more common.
Similar to cloudbursts, extreme atmospheric river events can create precipitation whiplash, especially in drought-ridden California, where water scarcity is already an issue of serious concern. According to the United States Drought Monitor, over 22 million people in California are currently living in areas of drought.
A 2019 study shows that despite the increase in extreme atmospheric river events, daily precipitation in California is projected to decrease, creating greater uncertainty for policymakers who are struggling to secure water for California’s citizens and its large agricultural industry, which produces nearly 50% of the United States’ vegetables and over 75% the country’s fruits and nuts.
Luna-Niño says that climate projections for the year 2100 suggest an increase in the frequency and intensity of atmospheric river events affecting the United States’ West Coast, “the reality is that these trends have not yet materialized.”
Still, these extreme rain events are already creating devastating losses for the people who inhabit regions at risk in California and the Himalayas. Norris says that California’s “existing infrastructure is likely to be insufficient for the expected intensification of extreme rainfall through the 21st century.”
“In heavily urbanized areas, there are too many impervious surfaces, and existing infrastructure was not designed with the potential storms of the future in mind,” he says, and recommends measures to include green infrastructure that employs natural processes to absorb heavy rain.
Meanwhile, in the mountainous regions of the Himalayas, experts recommend controlling construction in high-risk zones such as steep slopes and river banks, as well as implementing location-specific early alert systems that can give communities the crucial time they need to act in the event of a disaster.
Luna-Niño says that “stronger early warning systems, improved urban drainage, and ongoing efforts to enhance forecasts” need to be implemented to reduce the impact of future storms and reduce the impact of large disasters like the 2023 California atmospheric river storms and the 2025 Jammu and Kashmir cloudbursts, especially now that these meteorological phenomena are becoming more powerful than before.
